Im looking to build a nasty lil LT1 and im trying to figure out which way to go with my combo. What intake setups are your unning to support these power levels? Also what heads are you runnning? What were some of the problems you ran into, anything i should probably know? I know this aint cheap and thats not really a problem but i cant get too exotic. Id like to go 383 or possibly 396, but supplying these motors with the air they want at higher RPM seems to be an issue with LTX motors. Seeing which way might be the best to go for me.

 

best bet would probably be to use a solid roller cam and using a single plane intake converted to efi with an elbow and 90mm throttle body will supply plenty of air for the upper rpm power.

 

You want this power with a 6 speed or auto? Pumpgas or race fuel?

Gonna take at least a 383

Heads that flow at least 295 cfm(more is better)Pick your battles here, this is the key, remember you will lose 10-15% of your flow through the intake...unless it is DAMN good.

Big hyd roller or med size solid roller cam

High 8's in dynamic compression

Zero deck, tight quench

Good exhaust, Mufflex or similar true duals

Will be easier with a carb type or Stealth Ram manifold, has been done with a LT4 though

Naturally a good intake tract


Can be done with "off the shelf" stuff, but is much harder, also much easier with a six speed.

Just my .02



David

 

I see a 383 with LE heads and a custom cam by Bret Bauer (not just the ones he grinds for the LE setups, 6 speed/10bolt, and with supporting mods and dyno tune. 450 rwhp shouldnt be out of the question. But the question is how fast do you want to go and how much can you afford??

 

I see no reason why it can't be done with a 355 and good ported LT1 castings. Your going to have to know what your doing but I imagine over 450rwhp can be had with a hydraulic roller IMO

 

I know we are talkin numbers but the question is how much can you tolerate. Like to get 450 rwhp peak hp, you may be sacrificing alot, gas mileage, driveabilty, emissions for those it does matter. Or that you might need a sky high stall, or going to a soild roller set up, each person has a limit, you just need to find yours.

 

481 rwhp, hydraulic cam and great drivability.

But it’s been a lot of trial and error to find the combo. Personally won’t accept poor drivability and it’s just a matter of finding the right combo. Run solid roller cams as big as 253/262 with AFR 227 heads looking for power……hated the drivability and made less power than what I am currently.

To be honest..... never checked the gas mileage. Emissions? What's that? But I’m sure it would make well in excess of 460rwhp with cats on the car.

Have two more major mods to do with final camming to match the final combo and I’m pretty much maxed out on what to do with a standard 23 degree configuration. The next two mods are a set of 1 ¾-1 7/8’s stepped/merge collectors headers that just arrived (not installed yet) and some form of intake that is less restrictive than a stock modified intake. Current intake with monoblade has been welded above the injectors with the path straightened/ported and still shows -2 vacuum above 6000 rpm.

Great heads, cam that matches, stroker block with all the I’s dotted and T’s crossed and 450 rwhp N/A isn’t that hard to do, but don’t expect it to be cheap.

 

450rwhp is definitely attainable with a solid roller. It should be attainable with a big hyd. roller, at least through a 6spd. Even with Lloyd's stage 3 heads and cam, you're already pretty close, within 20-30hp. Milling the heads and using a thinner gasket to get to 11- 11.5:1 compression should actually do the trick, even with just a rebuilt 350 with aftermarket pistons. This is based on having LT's, 3" true duals, 58mm TB port matched to the intake, and a good tune. I don't see it being that hard honestly.

Jason

 

My baseline pulls a few weeks ago netted 472rwhp n/a. I also have a 383, solid roller comp grind 25x duration .650 lift. I'm running the AFR 220's, competition ported, no additional work other than what they came with from AFR. All the other misc. items required. I'm running an LT4 intake that is ported but not welded or otherwise modified and off-the-shelf hooker longtubes coated with mufflex Y. My gas mileage isn't that impressive but the car is streetable and will pull 6th gear @ 1500rpm. Good luck w/ the build! Remember, if it was as easy as it sounds on the board, everyone posting would have one!

I agree w/ Denny and the trial and error. As you get to 450rw and above, you enter some fairly uncharted territory and misc little problems surface that can be frustrating but in the end, its worth it.

 

Ron, I agree that it seems like everyone knows how to do it..but few do.

I know SAR2K did it with his ported lt1 heads and a very large hyd. roller on a stock bottem end(locked up auto and 3.73 stock rear end). Had a mean chop and was as finiky as a carb motor on start up untill worm. Gas milage sucked ...big time.

I make 476 through a 6 speed and 9" with 4.71s. I have a 355 with SAR2K Ported lt4 heads(flow right at 300 at peak..but STRONG mid lift numbers). Descent size solid roller and a lt4 intake. The intake has been extensivly worked. Stock crank, eagle rods, ross pistons. Nothing too fancy in the bottom end and off the shelf hooker long tubes. Oh..thats all on pump gas.

It can be done and there are several ways to get there. Just listen to the people that HAVE done it. Easiest way..afr 215 RR, Converted super vic, top mount throttle body,solid roller, super light rotating assembly that can live at 8500 rpms. Should make a good bit more than 450 at the tires if done right..should make 450 rwhp if done all wrong..lol. Hey..you didnt say that it had to be the cheapest way..lol.

 

I make 476 through a 6 speed and 9" with 4.71s. I have a 355 with SAR2K Ported lt4 heads(flow right at 300 at peak..but STRONG mid lift numbers). Descent size solid roller and a lt4 intake. The intake has been extensivly worked. Stock crank, eagle rods, ross pistons. Nothing too fancy in the bottom end and off the shelf hooker long tubes. Oh..thats all on pump gas.


I think you were around 430rwhp with that set up before the new heads right when you got into the tens?

Did you pick up that 46rwhp from those heads???????

 

yep..best pump gas pull was 428on the lt1 heads and worked lt1 intake and made it to the 10s in -800 DA air. I added the lt4 heads/intake. I also went from stock computer to dfi gen 7 which netted me no hp gain but tones more tuning and rpm cabality. The lt4 setup needs the rpms..the lt1 heads didn't. Please understand..these are not a off the shelf porting on the lt4s. Major work and bench time went into these heads/intake by Steve Stumph(SAR2K) when he was at Thunder racing. I went the times in sig in the bad air in the sig. Can't wait untill I make some good DA passes.

That bing said..his lt1 heads were his first shot at porting lt1 heads and he made 450 rwhp.

Sorry..not meaning to get this off topic. I guess most of this is revelant.

 

Don't be silly... you're one of the few who've done it and really have an idea what's involved.

My only experience here is with a 355 that made 491 rwhp. We used the AFR215RR, hydraulic roller, CFE sheet metal intake and alot of pricey topend stuff to get there. The bottom end was still relatively inexpensive as parts go. Of course I don't believe in spending more than is needed in that department.

Sadly enough, the car will never see the track. It's just another play toy for an eccentric friend of mine who thinks that only kids hang out on f-body message boards.

Hey, he's right........ although he left out the old stubborn asses.

David,
If you're losing 10-15% through an intake then it belongs in the trash can not on a performance engine. The CFE I mentioned lost a little better than 1%. My new intake is on the same scale. Of course sheetmetal generally does better but a good cast intake could be in the 5% range.

-Mindgame

 

This is all great stuff, love hearing about the different setups and what they can do. Ive wanted a nasty motor for a while but sent my $ on other stuff the last few years, this year im building a motor. Oh and there will be some pretty upset LS1 owners when its done hopefully.

 

Yes very nice.I'm lookin to join the club soon.