CamaroStylin

ok, so I'm looking at these 3 pages of head flow numbers i just downloaded for small block chevys, and I already had my heart set on some AFR 190cc aluminum heads, but they're discontinued and very expensive. I saw on here that the GM LT4 heads are pretty close in air flow. I was wondering, has anyone tried using these instead? if so, do they bolt right onto the SBC or is there some modification required? What kind of success has everyone had with these?
here are the flow numbers:
AFR:
.050 40/31
.100 71/67
.200 128/108
.300 195/156
.400 240/178
.500 260/190
.600 262/194

LT4:
.200 147/114
.300 197/141
.400 230/167
.500 250/180
.600 243/185

seems like it would be more cost efficient to buy the LT4s if it's just as high performance. what do you think??

Todd80Z28

LT4 heads go on LT1/LT4 style blocks (GenII small blocks). They are set up for reverse cooling, and lack the standard cooling passages for earlier small blocks. They can be made to fit GenI SBCs, but it isn't easy (or cheap).

If we're talking about Gen I aluminum heads, there are lots of choices.

AFR 195s- http://www.google.com/search?sourcei...nt&q=AFR+195cc

Edelbrock Etec (Vortec style head, require Vortec style intake)

Trick Flow 23*

All have pretty good flow numbers and characteristics for street motors. What are your goals for the motor? What other parts do you intend to use?

Todd

CamaroStylin

i'm aiming for a 499hp 355 TPI engine with the Holley Stealth Ram intake, AFR 190 heads, edelbrock performance RPM cam, TRW pistons and 10.5:1 compression

Damon

Like Todd said, LT-4 heads won't work on your earlier generation engine.

You may be interested to know that AFR 195 heads (still available) are EXACTLY the same as the 190s. The only difference is that the 195s come already port-matched to fit the SLIGHTLY larger runners of a Victor Jr. single plate carbureted intake manifold. Other than that, they are identical in every way.

I bought a set of 190s for my blower motor about 2 years ago and I crawled all over AFRs specs and talked extensively to their technicials, which is how I know this.

You should be able to run a set of 195s with your Holley Stealth Ram with no problems whatsoever since it has intake runners that are very close to the same size as the Vic Jr. intake they were built to fit originally.

In short- get the 195s and keep building it just like you planned. Your train is still on the tracks and headed in the right direction.

CamaroStylin

im sure the physical attributes are almost identicle, but the flow numbers are just a little different. That difference actually decreases the potential power of my setup more than you might think. here, let me show you what i came up with. the only difference in these two power ratings is the 190 and 195cc heads. here's the difference:

RPMs, Power, Torque
2000 -1/-3
2500 -2/-6
3000 -4/-5
3500 -3/-5
4000 -3/-4
4500 -4/-4
5000 -6/-6
5500 -8/-7
6000 -12/-11
6500 -15/-12
7000 -16/-13

I guess its not a big difference, but when youre building a performance engine you reach for every ft lb of torque, especially when its comming out of your own pocket
is it really safe to buy a used set of aluminum heads?? what do you guys think?

Damon

I think you're getting bad flow numbers to compare against. Back when I bought my AFR 190s they published flow numbers that were IDENTICAL for both heads. I can't imagine how the 195s could flow LESS than the 190s. AFR just doesn't do stuff like that.

I just went and checked on AFR's website and the flow numbers they are showing today for the 195s are still identical to the flow numbers they quoted on the 190s a while back.

I'd call and ask AFR their opinion on this. They'll tell you exactly what I did- the only difference is the size of the intake port opening. Everything else is the same- port minimum cross section, shape, bowls, valves, seats, chambers.

Todd80Z28

Without forced induction or Nitrous, I'd seriously doubt that you'll get 499HP out of a 355. And the Performer RPM cam is an older design. There are more aggressive designs out there in that range.

CamaroStylin

i actually think it's very likely. With the right parts matched up It's not out of reach at all. The L98 motor itself is an old design, but that doesnt mean it's not perfect for what my uses are for it. Its not always about having the top of the line equipment, it's about putting the right pieces together for the right application depending on your intended use. I COULD supercharge it and lower the compression and maybe even put some NOS on it, but i'm not going to because that's not reasonable for my application.
I talked it over with my stepbrother the other day. he is on the world wide nissan racing team and has an award winning chevy nova drag car that he built completely by hand-ran a 10.2 with the 406 that he had in it running 13:1 compression. pretty impressive if you ask me. he actually said it's extremely likely that this particular setup would reach those power numbers. he's lookin forward to driving it when im done
dont say something cant be done if youve never tried. that's the most important thing i've learned from all the reading i've done on engines before trying to design this particular one.

(BTW, he also used AFR heads on that 406. they were some like 260 heads or something that they dont even advertise because they're not something most people would use. he said he LOVED them, so i cant wait to get mine )

Todd80Z28

Ok, then, I'll say it again. You are not going to get 499hp out of the engine you've listed.

Damon will back me up- I'm certain.

It is rare, indeed, to see a hydraulic-cammed 350 pushing over 450hp in any case.

BamaZ28

I have to agree with him, I was hoping for 400HP outta my engine (check sig), and now it is closer to 315RWHP. It is just hard to get that much HP N/A outta a SBC

CamaroStylin

i did take into account that it's a hydrolic lifter, like youre saying, and I think im gonna give the AFR hydra rev kit a shot. what it does is it takes the added spring strength of the springs designed for a high RPM engine and instead of putting it on the plunger of the lifter, it puts it on the lifter body, giving an outstanding increase of power above 5000 rpms but without giving up any of the low end torque. have you guys had any experience with these kits??

BamaZ28

I had a friend that used the kit and swore by it, but I have heard many more say it is a waste of money.

Todd80Z28

I've used AFR's HydraRev before. It helps a few hundred RPM (it made the "nose over" go away at 6000, but I may have used the wrong springs/cam to begin with), but keep in mind that lifter weight and inertia is only part of the equation. The valve can "bounce" on the seat if the springs aren't strong enough, and the rev kit does nothing to help that. Can't go too strong on the spring, though, or the plunger goes. 400# over the nose is about it.

If you seriously MUST have 500hp from a naturally aspirated 350, I think you are going to have to rev it- to 7000 at least, likely a bit above. That means bigger port heads than what you are looking at. Solid roller cam with more duration than you're currently considering, and a slightly higher compression ratio. That's my guess, though.

Are you dorking around with Engine Analyzer or Desktop Dyno? I find those to be a bit optimistic, DD in particular.

You still haven't stated your intended use, or the vehicle it's going in. What do you want from this vehicle, never mind the 499 magic number?

Damon

I'm afraid I'm with Todd on this one. 500 HP from bolt-on AFR 190/195 heads seems unlikely. 450HP is realistic. 500HP you're gonna have to choose your cam very carefully and tune it within an inch of it's life.

I'm not talking about "theory" or ideal circumstances. Many people can plug in a combination that Desktop Dyno says will make 500HP. I'm talking about real world AS INSTALLED in the car. Imperfect exhaust, imperfect intake airflow, tuning that's reasonably close but not tweaked dead-on.

The number of times a "500HP" engine has only put out 400 or less under actual as-installed conditions is a lot. It can be done, but it ain't easy.

CamaroStylin

nothin worth having ever is

the engine is going in my 88 camaro. It'll be in use with a T-56 transmission (keep in mind, its 499 at the flywheel, not the wheels). I may give the hydra rev kit a chance-it seems for 229 bucks it's worth it even if it only gives an extra 40 hp above 6k.

to save cost and help me get the engine in the car faster, i may use a 700R4 tranny until i can get enough money together for a t-56. how much power do you guys think a dead stock 700R4 could hold without problems?

i was told a story by a guy who works at a local engineering testing facility that his buddy had an 80s corvette with the 700r4 and two times within a month he blew the reverse gear because it was stamped metal and not strong enough. Is this an issue with more powerful engines on the 700R4?

and to answer your question, this engine will be used in my daily driver. If i had it in a strip car i'd buy a new crank, enlarge the oil return holes, put on some insanely strong springs and push rods and run that babby at 7500 rpms all the way down the track, but this is as extreme as i feel i can get without spending TOO MUCH money on gas and also keeping the car within a reasonable power level for the street