dyno runs on the 408

finally got around to it today. was done at norris motorsports.

review of setup
408
11.5:1 compression
SLP lid
vinci ported MAF ends
NX 85mm TB
NX intake
42# SVO injectors
2.02/1.60 ported 4.8L heads
232/240 .551/.551 (1.7 ratio) 117 LSA
crane 1.8 shaft rockers brings lift to .589/.589
dynatech 1 3/4 stepped 1 7/8 headers w/3" collectors
bassani tru-duals 2.5" w/x-pipe
yank py3400 converter
3.73 gears
275/50-15 nitto DRs
250 NX NXL DP nitrous

this run was on motor converter unlocked

http://www.stealthram.com/familypics/formula00/dynosheet/408/naconverterunlocked.jpg

this run was on motor, converter locked 21* timing

http://www.stealthram.com/familypics/formula00/dynosheet/408/naconverterlocked21.jpg

same run with 26* timing

http://www.stealthram.com/familypics/formula00/dynosheet/408/naconverterlocked26.jpg

this run is with the 250 shot. tires spun on the dyno and didn't hook until almost 5500 rpms

http://www.stealthram.com/familypics/formula00/dynosheet/408/nitrousrpm.jpg

here's the same run using mph, so you can get a little better view of the run

http://www.stealthram.com/familypics/formula00/dynosheet/408/nitrousmph.jpg

Definitely the wrong heads/cam for an NA setup. Retarding that tiny camshaft would help immensely.

Don't take it the wrong way, but you're giving up ALOT of NA power... :think: Even $999 Patriot LS6 heads and a more aggressive cam would have made an additional 40+ rwhp on motor while making no difference on driveability or power on nitrous. Whoever designed that setup didn't do their homework.

:think:

Mike

Agreed.

Unlocked numbers or not... your peak flow numbers are at way higher lift and the heads arent the best.

may I suggest livernois, they are on sale too :)

Definitely the wrong heads/cam for an NA setup. Retarding that tiny camshaft would help immensely.

Don't take it the wrong way, but you're giving up ALOT of NA power... :think: Even $999 Patriot LS6 heads and a more aggressive cam would have made an additional 40+ rwhp on motor while making no difference on driveability or power on nitrous. Whoever designed that setup didn't do their homework.

:think:

Mike


i don't mind having a discussion about it, so here goes....

yeah, me and vinci high performance didn't do our homework at all. just figured we would throw something in there. do you know the flow specs on my heads?


let's compare the patriot heads:

patriot LS6 style heads 2.02/1.57 3.905 bore flow
mine 2.02/1.60 3.905 bore flow

lift -------- p i/e ----------- m i/e
.100 ------ 72/65 ---------- n/a
.200 ------ 140/124 ------- 145/109
.300 ------ 202/160 ------- 209/148
.400 ------ 244/196 ------- 253/174
.500 ------ 280/220 ------- 288/181
.600 ------ 304/229 ------- 301/205

my heads beat their comparable heads on the intake side. so, what would another 25-30 cfm on the exhaust side do for me?


patriot LS6 style heads 2.08/1.60 4.125 bore flow
mine 2.02/1.60 3.905 bore flow

lift -------- p i/e ----------- m i/e
.100 ------ 78/66 ---------- n/a
.200 ------ 147/124 ------- 145/109
.300 ------ 209/164 ------- 209/148
.400 ------ 255/206 ------- 253/174
.500 ------ 296/229 ------- 288/181
.600 ------ 322/237 ------- 301/205

looking at their stage III with a much larger intake valve isn't much better on the intake side again. again, what would another 25-30 cfm on the exhaust side do for me? and these patriot heads were flowed with a much larger bore size. at this point, i can't see spending $1000 for only a better exhaust port flow side.

now onto the cam. i've seen smaller cams than mine make more power. so, tiny cam it isn't. i could probably get more torque out of it by bringing the LSA in tighter, no debate there. driveability is in the eye of the owner of the car.

Agreed.

Unlocked numbers or not... your peak flow numbers are at way higher lift and the heads arent the best.

might want to review my above post about my head flow. peak flow numbers don't make a head better than another. also, remember the cam lift is with 1.7 rockers. add the 1.8 ratio and it comes to .589. i'll edit my initial post to clarify that.

Flow numbers are only part of the equation.

You're contradicting yourself. First you say that your heads "beat" Patriot's because of the flow numbers, then in the next post, you say that flow numbers aren't everything. So, which is it? :think: :lol:

Regardless, I've never seen 4.8L or 5.3L heads make impressive power on a stroker motor and your car is proof. Add a tiny cam that belongs in a stock-cube motor and you have a recipe for mediocrity.

BTW, I had some Patriot Stage II 2.02/1.60 LS6 heads (that your 4.8L supposedly beat) and a 238/240 110LSA -4 in my car that put down 530/505 with a 408..... roughly 90 more rwhp than your locked converter car. Not all flow benches are the same. Yours might flow 300 on their advertised flow bench and when you put it on another, it might only flow a true 270.

Darts are pretty consistant -- advertised at 300ish cfm max and actually were flowed at Meaux's in the mid 290s.. I guess that's why my heads/cam car put down 471/416.

Anyway...like I said before:
The heads/cam/intake manifold in your 408 is choking it pretty badly. Take it for what it's worth...If you intend on spraying it into the 650+RWHP range, then have fun with it.

Cheers.

Flow numbers are only part of the equation.

You're contradicting yourself. First you say that your heads "beat" Patriot's because of the flow numbers, then in the next post, you say that flow numbers aren't everything. So, which is it? :think: :lol:

read a little closer. i said peak flow numbers don't make a head better than another. that was in response to his statement about peak numbers.

Regardless, I've never seen 4.8L or 5.3L heads make impressive power on a stroker motor and your car is proof. Add a tiny cam that belongs in a stock-cube motor and you have a recipe for mediocrity.

once ported, what does it matter if they were originally 5.3 or 5.7 heads?

BTW, I had some Patriot Stage II 2.02/1.60 LS6 heads (that your 4.8L supposedly beat) and a 238/240 110LSA -4 in my car that put down 530/505 with a 408..... roughly 90 more rwhp than your locked converter car. Not all flow benches are the same. Yours might flow 300 on their advertised flow bench and when you put it on another, it might only flow a true 270.

Darts are pretty consistant -- advertised at 300ish cfm max and actually were flowed at Meaux's in the mid 290s.. I guess that's why my heads/cam car put down 471/416.

again i said my heads 'beat' on the intake side. your telling me to spend $1000 for heads that only flow better on the exhaust side. so, i'll ask again, what will another 25-30 cfm on the exhaust side do for me?

as far as your 90 rwhp more goes, let's see, more intake duration (6* and you call my cam tiny), 7* less LSA which gives you a larger mid range boost over mine (way more overlap than my cam has), retarded 4* for more upper rpm power (mine is ground advanced 5*), 6 speed trans versus auto with 3400 stall, and don't know your rear gear.

Anyway...like I said before:
The heads/cam/intake manifold in your 408 is choking it pretty badly. Take it for what it's worth...If you intend on spraying it into the 650+RWHP range, then have fun with it.

Cheers.

now it's heads/cam/intake manifold. your first post only said heads/cam. why is the NX intake a restriction? any flow numbers comparing it to other manifolds to support your claim if it being a restriction now?

i appreciate the conversation. do you have the graph of your 408 motor up somewhere? i'd like to take a look at it.

you already had the heads and cam right?

was that your reason for not going bigger....at least the cam. with the expense of heads i can understand that.

but i would think you could have picked up a bigger cam for cheap used someplace. and made alot more power.

just curious as to why you started off with such a small cam...on a big motor?

I hate to say this because nobody likes criticism, but I agree that you're leaving some HP on the table. That cam is really on the small side for a 408 and I think you'd be surprised at how well a mid-245 cam can drive when tuned properly. I don't know what kind of work was put into the 4.8 heads, but flow numbers aren't the only thing to look at. Mike is a really good guy to work with, so don't be afraid to get his opinion. The bottom line is: Are YOU happy? If so, anything else is purely academic...
FWIW, I know you can't compare a M6 to a A4 on the dyno, but my little/low-budget/LS6 intake chokin'/not all bolt-on havin'/old-school Hooker header wearin'/Y-pide saddled/5.3 headed 383 makes better N/A numbers and about the same nitrous numbers (more torque, tho) on a TNT wet 150 shot. Not saying this to be a d*ck, just to give you some background on why I think your numbers are off. Best of luck to you!

Don't miss the killer nitrous system he has. He built this motor to spray......

once ported, what does it matter if they were originally 5.3 or 5.7 heads?

as far as your 90 rwhp more goes, let's see, more intake duration (6* and you call my cam tiny), 7* less LSA which gives you a larger mid range boost over mine (way more overlap than my cam has), retarded 4* for more upper rpm power (mine is ground advanced 5*), 6 speed trans versus auto with 3400 stall, and don't know your rear gear.

now it's heads/cam/intake manifold. your first post only said heads/cam. why is the NX intake a restriction? any flow numbers comparing it to other manifolds to support your claim if it being a restriction now?

i appreciate the conversation. do you have the graph of your 408 motor up somewhere? i'd like to take a look at it.

LS6 heads are a COMPLETELY different animal than LS1 heads. Properly ported and setup LS6 heads can support upwards of 650-700 horsepower with no problem while getting the intake runners around 240cc+. In fact, a few LSx records were set with these heads including Futral's 9.9x@137 stock-cubed 6-speed run.

When you lock-up the converter on a dyno run you're taking out the "autos make around 5% less horsepower to the wheels than a 6-speed car" standard. Locked-up you're making 440rwhp. I made 530rwhp, but it's actually a little bit more than that since I did it through a Vette IRS. Basically when you compare my Vette IRS 6-speed to your locked-converter auto with a solid-rear, it's the same thing.

FAST 90/90s make the biggest power. That's why every big-power setup uses them (or a $2000 sheetmetal intake).

Looking at your dynograph on motor on the 26* locked up chart where you made 440:
You're severely undercammed. You're peaking at around 5500-5750 and start dropping there. Your car should be peaking at around 6000 rpm at the least and holding it for a few hundred RPM. Your cam isn't setup correctly at ALL for this motor and the graph shows it. 232/240 and 5* advanced on a 408? Why are you making the cam act SMALLER by running it advanced?! You should retard it at the very least (actually you should step up the cam size). 117 LSA?! You aren't running a turbo or a blower. There's just no need for it on a NA or "nitrous" motor.

My $.02 ;)

My dynochart before and after Futral's tune.

http://kraest.cz28.com/dyno.jpg

you already had the heads and cam right?

was that your reason for not going bigger....at least the cam. with the expense of heads i can understand that.

but i would think you could have picked up a bigger cam for cheap used someplace. and made alot more power.

just curious as to why you started off with such a small cam...on a big motor?

heads were from the wife's motor. cam is new.

how can my cam be small, when kraest's cam is right along the same duration?
238/240 110LSA -4 - he has 6* more intake, same exhaust, 7* less LSA and retard 4*.

not saying that i didn't leave some power on the table with the 117LSA. i knew that was coming. there's a definition of driveability that means different things to everyone. and tuning for another.

I hate to say this because nobody likes criticism, but I agree that you're leaving some HP on the table. That cam is really on the small side for a 408 and I think you'd be surprised at how well a mid-245 cam can drive when tuned properly. I don't know what kind of work was put into the 4.8 heads, but flow numbers aren't the only thing to look at. Mike is a really good guy to work with, so don't be afraid to get his opinion. The bottom line is: Are YOU happy? If so, anything else is purely academic...
FWIW, I know you can't compare a M6 to a A4 on the dyno, but my little/low-budget/LS6 intake chokin'/not all bolt-on havin'/old-school Hooker header wearin'/Y-pide saddled/5.3 headed 383 makes better N/A numbers and about the same nitrous numbers (more torque, tho) on a TNT wet 150 shot. Not saying this to be a d*ck, just to give you some background on why I think your numbers are off. Best of luck to you!


if i didn't want criticizm, i would not have posted up. i'm all about discussions.

again with the small cam. how is it small, when kraest's cam is 238/240 and mine is 232/240???? i've seen a 402 in a GTO make 450 rwhp with a 224/224 cam.

my nitrous torque numbers aren't accurate for a peak number. as i stated, the tires spun on the dyno until about 5500 rpms when the dynojet started reading. you can see it on the dyno sheet. that will explain why you have a higher torque peak number than me with your 383.

am i happy with it? for having 663 rwhp, sure. not too many everyday driving, full weight carrying cars are out there.

LS6 heads are a COMPLETELY different animal than LS1 heads. Properly ported and setup LS6 heads can support upwards of 650-700 horsepower with no problem while getting the intake runners around 240cc+. In fact, a few LSx records were set with these heads including Futral's 9.9x@137 stock-cubed 6-speed run.

When you lock-up the converter on a dyno run you're taking out the "autos make around 5% less horsepower to the wheels than a 6-speed car" standard. Locked-up you're making 440rwhp. I made 530rwhp, but it's actually a little bit more than that since I did it through a Vette IRS. Basically when you compare my Vette IRS 6-speed to your locked-converter auto with a solid-rear, it's the same thing.

FAST 90/90s make the biggest power. That's why every big-power setup uses them (or a $2000 sheetmetal intake).

Looking at your dynograph on motor on the 26* locked up chart where you made 440:
You're severely undercammed. You're peaking at around 5500-5750 and start dropping there. Your car should be peaking at around 6000 rpm at the least and holding it for a few hundred RPM. Your cam isn't setup correctly at ALL for this motor and the graph shows it. 232/240 and 5* advanced on a 408? Why are you making the cam act SMALLER by running it advanced?! You should retard it at the very least (actually you should step up the cam size). 117 LSA?! You aren't running a turbo or a blower. There's just no need for it on a NA or "nitrous" motor.

My $.02 ;)

My dynochart before and after Futral's tune.



what makes it the cam's fault? why not another valvetrain issue? no doubt i should be peaking higher, but what's stopping it? the 5* advanced is ground into the cam. i zero'ed the cam. that's the way vinci does their cams. is that the reason why? there's another person with this same exact cam in a larger cube motor in a vette. i'm trying to get ahold of his graph and see how his did.

i might try retarding the cam. it'll only take about 1.5 hours to do it. i have an adjustable timing chain. all it's going to do is just move the rpm band up.

heads? who knows for sure without trying. i still don't see what 25-30 cfm on the exhaust side will do for me.

what makes it the cam's fault? why not another valvetrain issue? no doubt i should be peaking higher, but what's stopping it? the 5* advanced is ground into the cam.

i zero'ed the cam. that's the way vinci does their cams. is that the reason why?

i might try retarding the cam. it'll only take about 1.5 hours to do it. i have an adjustable timing chain. all it's going to do is just move the rpm band up.

heads? who knows for sure without trying. i still don't see what 25-30 cfm on the exhaust side will do for me.

When you say "zeroed", do you mean you installed it straight up or 5 degrees retarded to get it to zero? If you installed it straight up, then it's 5 degrees advanced and will kill horsepower on a large cube motor because you're making the cam act smaller than what it is -- I guarantee you find much more power retarding the cam until it isn't advanced at all (retarding it 5 degrees) (or getting a new cam altogether ;) )

Once again, you're talking about peak numbers, which don't mean anything -- flow numbers can differ 30-40cfm from bench to bench and honestly you can make flow numbers say anything you want. Regardless, those heads aren't moving enough air and the cam is too small -- and it's shown on your dynograph. A low peak and not carrying the rpm like that shows restriction in the setup.

Mike

When you say "zeroed", do you mean you installed it straight up or 5 degrees retarded to get it to zero? If you installed it straight up, then it's 5 degrees advanced and will kill horsepower on a large cube motor because you're making the cam act smaller than what it is -- I guarantee you find much more power retarding the cam until it isn't advanced at all (retarding it 5 degrees) (or getting a new cam altogether ;) )

straight up.

what makes your cam larger than mine? you keep saying my cam is small. mine is a 232/240 and yours is a 238/240. the major differences are the LSA and you have it retarded 4*. i agree than with it being advanced it's going to have less peak hp. and with a 117 LSA it's going to have less peak torque and possibly overall. but to say my cam is small, especially when you are running the almost same duration, i just don't get. you made 530 rwhp with your 'small' cam.

Once again, you're talking about peak numbers, which don't mean anything -- flow numbers can differ 30-40cfm from bench to bench and honestly you can make flow numbers say anything you want. Regardless, those heads aren't moving enough air and the cam is too small -- and it's shown on your dynograph. A low peak and not carrying the rpm like that shows restriction in the setup.

Mike

i am not talking peak numbers. i'm looking at each lift point on the heads and seeing an average of 25-30 cfm of flow. if the exhaust side is backing up the flow, then i'm all for changing heads. i've already looked into the patriot and AFR heads. called tony mamo and had a small conversation about it.

ok found the patriot LS6 heads. it's on their new products page even less than 25 cfm on the exhaust side average. 227 cfm intake for patriot and 224 cc runner on mine.

lift -------- p i/e ----------- m i/e ------ diff
.100 ------ 79/81 ---------- n/a
.200 ------ 145/120 ------- 145/109 --- 0/+11
.300 ------ 204/164 ------- 209/148 --- -5/+16
.400 ------ 251/191 ------- 253/174 --- -2/+17
.500 ------ 282/206 ------- 288/181 --- -6/+14
.600 ------ 300/214 ------- 301/205 --- -1/+9


yeah, yeah every flow bench is different. who's is right? i just can't see spending $1100 for heads that just don't flow any better than mine. their LS6 STYLE heads flow better than their actual LS6 heads.

a low peak and not carrying through the rpms doesn't only mean theres a restriction in the set up. i'm thinking more of a valve train issue. looking into the valve train issue as we speak.

another thing. after 6000 rpms, the knock sensors go off to the tune of 4* retard, according to my HPTuners. this is with 26* and 21* of timing. so that tells me it's not real. this is pointing me towards valvetrain still.

the MAP readings after 6000 rpms were fluctuating at 94-95 kPa. now, with the engine off the kPA reading is at 102 kPA. so, maybe there is a restriction, but that would be somewhere before the heads. is it the SLP airlid, the ported MAF ends not large enough, the 85mm NX TB not large enough?

not going to say the heads aren't hurting airflow. i've always had that in the back of my mind. especially that GTO with the 224/224 and AFR 205 heads that made 450 rwhp.

as far as the intake itself, i don't have any flow numbers on it. so, i can't say if a FAST 90 would do any better. it's a special intake that NX designed to compliment the NXL direct port nitrous system. there are no nozzles. the intake is drilled to be the nozzle. last italked with NX, there were only 5 other manifolds out in the world being used. they had 12 made. here's what that looks like:

http://www.stealthram.com/familypics/formula00/408/nx/linesonintake.jpg

i am very impressed with your 530 rwhp motor. gives me something to ponder. with the only main difference being retarded and having less LSA, i would point more towards the cam as being my issue for not having as much power. then again, i need to deal with the valvetrain issue first.

don't think that i do not appreciate your opinions. i really do. as i said, if i didn't want criticizm, i would never have posted. keep the ideas coming.

if i didn't want criticizm, i would not have posted up. i'm all about discussions.

again with the small cam. how is it small, when kraest's cam is 238/240 and mine is 232/240???? i've seen a 402 in a GTO make 450 rwhp with a 224/224 cam.

my nitrous torque numbers aren't accurate for a peak number. as i stated, the tires spun on the dyno until about 5500 rpms when the dynojet started reading. you can see it on the dyno sheet. that will explain why you have a higher torque peak number than me with your 383.

am i happy with it? for having 663 rwhp, sure. not too many everyday driving, full weight carrying cars are out there.

You may think that isn't a "small" cam, but to most of your stroker-peers, it is. My little 383 uses a COMP XER244. I'll bet that GTO would make over 500rwhp with a bigger cam, so I'm not sure what the point is...

You don't know what rwtq you have on the squeeze, but I'd wager that I'm right there. Again, no bravado, just pointing out that you have 25 more c.i. and 100HP bigger shot (DP too!) and aren't making more power than me. That's why I think you have room to improve.

If you are happy with it, that's all that matters. We are just suggesting that since you went to all this trouble, why not get everything you can within reason? A good, patient tuner (like Mike) can make a hairy engine daily-drivable...

You may think that isn't a "small" cam, but to most of your stroker-peers, it is. My little 383 uses a COMP XER244. I'll bet that GTO would make over 500rwhp with a bigger cam, so I'm not sure what the point is...

point being is both of you keep telling me i need a bigger cam. the gto made more rwhp than me and a much smaller cam. plus kraest's cam is a 238/240 and mine is a 232/240. so i keep wondering why you two keep telling me i need a bigger cam. maybe a different profile, but not a larger one. after all kraest made 90 rwhp more than me with only 6* more on the intake side.

You don't know what rwtq you have on the squeeze, but I'd wager that I'm right there. Again, no bravado, just pointing out that you have 25 more c.i. and 100HP bigger shot (DP too!) and aren't making more power than me. That's why I think you have room to improve.

using my na numbers as being square, my assumption would be in the 650 rwtq range. i gained 225 rwhp on the nitrous. but, it's nothing more than a guess.

If you are happy with it, that's all that matters. We are just suggesting that since you went to all this trouble, why not get everything you can within reason? A good, patient tuner (like Mike) can make a hairy engine daily-drivable...

am i happy i made 663 rwhp, sure. i was hoping for more on motor than what it did. there are issues that need to be addressed. i am self tuning as well. and i'm nothing special in that area. i've been tuning since april on this motor. never tuned an LS1 before. so i jumped head first into something huge.

i appreciate the suggestions. gives me something to ponder on.

straight up.

what makes your cam larger than mine? you keep saying my cam is small. mine is a 232/240 and yours is a 238/240. the major differences are the LSA and you have it retarded 4*. i agree than with it being advanced it's going to have less peak hp. and with a 117 LSA it's going to have less peak torque and possibly overall. but to say my cam is small, especially when you are running the almost same duration, i just don't get. you made 530 rwhp with your 'small' cam.


6 degrees of duration @ .050" can make a huge difference and pick up a ton of power if the cam is already small (and yes... mine was on the small side as well.) It's really not in your best interest to put anything less than a 24x duration cam in a 400+ cube motor if you want to make power. Mine was retarded a total of 8 degrees since it was ground on a +4 and would up being on a -4. That's one of the main reasons my setup made power like it did despite the smaller cam. If it was on a +4, it would have peaked very early like your car did. The 110 vs the 117 LSA is going to be another huge factor on NA power. There's absolutely no reason to put that kind of cam in there if you aren't running a blower. 112 would have been enough for a nitrous application or a 114 at the absolute most... you're not making positive manifold pressure with nitrous.


i am not talking peak numbers. i'm looking at each lift point on the heads and seeing an average of 25-30 cfm of flow. if the exhaust side is backing up the flow, then i'm all for changing heads. i've already looked into the patriot and AFR heads. called tony mamo and had a small conversation about it.


I'm not talking about peak numbers. I'm talking about flow numbers in general. They can all be adjusted to what they want them to be. :shrug:


ok found the patriot LS6 heads. it's on their new products page even less than 25 cfm on the exhaust side average. 227 cfm intake for patriot and 224 cc runner on mine.

lift -------- p i/e ----------- m i/e ------ diff
.100 ------ 79/81 ---------- n/a
.200 ------ 145/120 ------- 145/109 --- 0/+11
.300 ------ 204/164 ------- 209/148 --- -5/+16
.400 ------ 251/191 ------- 253/174 --- -2/+17
.500 ------ 282/206 ------- 288/181 --- -6/+14
.600 ------ 300/214 ------- 301/205 --- -1/+9


yeah, yeah every flow bench is different. who's is right? i just can't see spending $1100 for heads that just don't flow any better than mine. their LS6 STYLE heads flow better than their actual LS6 heads.


It all depends on who you talk to. You can see how well the heads have been worked by the power you produce. Having high flow numbers doesn't mean that a head has great port velocity -- I've seen plenty of 300 cfm heads that weren't worth a **** because they got very turbulent and messy and were simply "hogged out" to achieve "flow numbers." On the other hand, I've seen "true" 270cfm heads that would outperform those trash 300cfm heads any day of the week.



another thing. after 6000 rpms, the knock sensors go off to the tune of 4* retard, according to my HPTuners. this is with 26* and 21* of timing. so that tells me it's not real. this is pointing me towards valvetrain still.


My 408's valvetrain sounded like a bag of marbles and the knock sensor agreed. :lol: I picked up around 15-20rwhp on the dyno by simply having Allan desensitize them.


the MAP readings after 6000 rpms were fluctuating at 94-95 kPa. now, with the engine off the kPA reading is at 102 kPA. so, maybe there is a restriction, but that would be somewhere before the heads. is it the SLP airlid, the ported MAF ends not large enough, the 85mm NX TB not large enough?


I was using the LS2 TB and the stock Corvette MAF with a Haltech Stinger/Vararam combo. I don't think that's your problem. Obviously you'll make a tiny bit more power by taking off the air cleaner, but do you really want to?



not going to say the heads aren't hurting airflow. i've always had that in the back of my mind. especially that GTO with the 224/224 and AFR 205 heads that made 450 rwhp.


AFR has spent tens of thousands of dollars designing their heads. I've seen those heads make some really great numbers, but they are very pricey.


as far as the intake itself, i don't have any flow numbers on it. so, i can't say if a FAST 90 would do any better. it's a special intake that NX designed to compliment the NXL direct port nitrous system. there are no nozzles. the intake is drilled to be the nozzle. last italked with NX, there were only 5 other manifolds out in the world being used. they had 12 made. here's what that looks like:

http://www.stealthram.com/familypics/formula00/408/nx/linesonintake.jpg


Your manifold looks awesome. However, I don't know how it will perform for an NA application ;) I'm sure it needs to be port-matched to the heads if it hasn't been already.


i am very impressed with your 530 rwhp motor. gives me something to ponder. with the only main difference being retarded and having less LSA, i would point more towards the cam as being my issue for not having as much power. then again, i need to deal with the valvetrain issue first.



Good luck in your quest ;) :thumb: :cz28:

i still don't see what 25-30 cfm on the exhaust side will do for me.

Let more air out??? Why do you keep insisting that exhaust flow isn't important? There's more to making power than just getting air into the cylinders. You have to get the exhaust out fast enough to let a full intake charge in. If your exhaust is choked then you can do anything you want to the intake side without gaining a single HP.
This can be bandaided somewhat by more overlap and more exhaust duration.

Let more air out??? Why do you keep insisting that exhaust flow isn't important? There's more to making power than just getting air into the cylinders. You have to get the exhaust out fast enough to let a full intake charge in. If your exhaust is choked then you can do anything you want to the intake side without gaining a single HP.
This can be bandaided somewhat by more overlap and more exhaust duration.

i never said it wasn't important. i said what will another 25-30 cfm of flow do for me. exhaust is under high pressure as it is. if i can get another 90+ rwhp by changing heads and cam, i'm all for it. but, if all i get is 40 rwhp, i'm not interested in spending $3000 for only a small to moderate gain.

kraest, you've been a great help.

kraest, you've been a great help.

No problem. ;) :cz28:

I'd start by retarding your cam 5 degrees and see what happens. ;)

Are you running the Cometic .040" gaskets? These motors like compression in the low 12s on 93 octane.

See what retarding the cam does. If it makes a big difference, you might want to go back to the drawing board and swap to a different cam.

As far as heads go:
Unfortunately I no longer see the heads that I had on my car on Patriot's site. The only REAL LS6 (243 casting) head they offer appears to be a 227cc 2.00/1.55 valve that flows around 300/213 peak cfm @ .600 on a 3.905" bore. That's a FAR cry from my 2.02/1.60 240cc that flowed somewhere in the low 330s @ .600"

Mike

unfortunately, i cannot use MLS gaskets with these heads. they have the service notch on the deck surface.

at the suggestion of a member of kraest, he said to retard the cam to make more power as his opinion is the cam being ground 5* advanced is limiting my peak hp at 5700 rpms. well, it didn't go as planned.

blue line = straight up
red line = 5* retard

http://www.stealthram.com/familypics/formula00/dynosheet/408/camretard.jpg

I think it is interesting how much of a change it made. What about going the other way 5deg?

I think it is interesting how much of a change it made. What about going the other way 5deg?

extrapolating from what just happened, the guess would be a gain of the same amount. but the cam is already ground 5* advanced to begin with. but, i don't see that happening. looks like the homework on the design of the cam was already done.

That's completely ridiculous. Damn. Was that with the converter locked? How much did you retard the cam?

BTW, your A/F is getting lean on that dyno run compared to the previous one. Should have added more fuel.

Well, it looks like the heads are to blame. There should be NO reason that the graph did that when you retarded the cam. The power is still crapping out before 6000 rpm and falling too quickly -- very similar to my buddy's 205cc Dart heads on his 383 LS1.

I still say that the cam is too small and the heads don't flow enough air for that big cube motor. It's sad that even retarding the cam couldn't buy you some power.

That's completely ridiculous. Damn. Was that with the converter locked? How much did you retard the cam?

converter locked. as stated, in the post, i retarded it 5*.

BTW, your A/F is getting lean on that dyno run compared to the previous one. Should have added more fuel.

only made one pull with same tune as the other pulls. i'll just put the cam back where it was. took me just under an hour to pull the front off and change the degree setting on the timing chain.

Well, it looks like the heads are to blame. There should be NO reason that the graph did that when you retarded the cam. The power is still crapping out before 6000 rpm and falling too quickly -- very similar to my buddy's 205cc Dart heads on his 383 LS1.

I still say that the cam is too small and the heads don't flow enough air for that big cube motor. It's sad that even retarding the cam couldn't buy you some power.


i agree on the heads, especially after this. i figured they would hold me back, but not this much. still have to figure out the drop in the 6k range. i keep being told it's valve float. with 3/8" pushrods and shaft mount rockers, and the latest crane 833 springs, i'm at a loss there. unless the spring setup isn't working out. might need to increase pressure.

i agree on the heads, especially after this. i figured they would hold me back, but not this much.still have to figure out the drop in the 6k range. i keep being told it's valve float. with 3/8" pushrods and shaft mount rockers, and the latest crane 833 springs, i'm at a loss there. unless the spring setup isn't working out. might need to increase pressure.

I think it's a combination of both the cam and the heads, but leaning more towards the heads. I doubt it's valve float with those springs -- They appear to be pretty decent.

I ran stock rockers and Patriot Golds on my 408. No problems with valve float even with the rev limiter set at 7200 rpm.

Mike

i keep being told it's valve float. with 3/8" pushrods and shaft mount rockers, and the latest crane 833 springs, i'm at a loss there. unless the spring setup isn't working out. might need to increase pressure.

If your up for a little more experimentation. Throw in a set of hardened stock dia. pushrods and your stock rockers and see if the ''valve float'' goes away.

If your up for a little more experimentation. Throw in a set of hardened stock dia. pushrods and your stock rockers and see if the ''valve float'' goes away.

converting back to stock rockers will be a little tough to do. to fit the crane shaft mount rockers, you have to mill the heads .170" where the rocker stands are. then drill the holes and tap to 3/8-16 thread.

converting back to stock rockers will be a little tough to do. to fit the crane shaft mount rockers, you have to mill the heads .170" where the rocker stands are. then drill the holes and tap to 3/8-16 thread.

OK so that won't work. I was just thinking that maybe your valve train components were too heavy and causing bad vibrations/harmonics with the heavy springs. Try a different brand of spring maybe?

OK so that won't work. I was just thinking that maybe your valve train components were too heavy and causing bad vibrations/harmonics with the heavy springs. Try a different brand of spring maybe?

well, i don't see what i have as being a problem. here's where vinci used the 1.7 shaft with the 833 springs and took the motor to 7000 rpms with no issues. i'm even using 3/8" pushrods. granted i'm using 1.8 rockers. so, something is amiss. for now, i'll just continue to shift at 6200 rpms. i'll work on getting the newest design AFR heads that tony and i talked about next year.

http://www.vincihiperformance.com/C6%20AUTO%20HEAD%20&%20CAM%201.7%20SHAFT%20GRAPH.HTML

well, i don't see what i have as being a problem. here's where vinci used the 1.7 shaft with the 833 springs and took the motor to 7000 rpms with no issues. i'm even using 3/8" pushrods. granted i'm using 1.8 rockers. so, something is amiss. for now, i'll just continue to shift at 6200 rpms. i'll work on getting the newest design AFR heads that tony and i talked about next year.

http://www.vincihiperformance.com/C6%20AUTO%20HEAD%20&%20CAM%201.7%20SHAFT%20GRAPH.HTML


You can't compare that to yours. Different rocker ratio means that for a given engine rpm and cam lift the the valve end of the rockers and valves are moving faster. And the heavier pushrods could be the blame.