Hi guys,

My engine builder is suggesting I go with a mild set of alumunim heads, like 170cc edelbrocks or something like that. I was planning on going with closer to a 200cc head, probably a Topline head.

Engine specs are...
* forged crank & pistons
* 6in rods
* 10 - 10.5 compression range
* mild hyd roller cam around .5 lift 210 duration

I figure this motor is not going to be short on low rpm torque, so I can sacrafrice some torque for a bit of HP by going with a larger head. This motor will only see like 6000rpm so maybe a 180cc head is okay.

Thanks in advance for any help...

--Jack

 

I'd think your 400, like you said, would have tons of low end, that's why I'd go with a cam somewhere around 220-230@.050 (with as much lift as practical)which will pull strong upto 5500rpm and a cylinder head somewhere around 190min-210cc. 180cc head with a cam of 210@.050 would give you tons, I mean tons of low end while sacrificing top-end .I'm not sure if you mentioned the intake system or the purpose of the engine, but a 400 cammed to pull strong upto 5500rpm needs at least 220@.050 and a 190cc intake port and will still make around 400lbs of toq @ around 2500rpm. Although not too high for an aluminum head, be careful with 10.5:1 and a short duration (210) cam, try to keep lobe separation tight (110). Just my .02 on what I've experienced. I have a 440hp 406 SR engine and working on a 500hp 383 with a single plane conversion. Good Luck!


[Modified by JUAN J SANCHEZ, 10:11 PM 7/26/2003]

 

I just put in a roller .225/.233 with 280/289 Adv Duration, it is not too much cam and is very streetable.

When I called CompCams they recommended a .224/.230

If I did it again I would go .230/236 or something in that range.

It depends on the heads and your peak shift goals, peak HP, I have 215 CC heads

BTW my midrange torque and HP are incredible

Dyno results soon.


[Modified by ld85, 10:13 AM 7/27/2003]

 

Okay, I think I'm going to step my cam up to the .509/.528 with a 230 duration @ .5 I'll go with the 200cc heads.

I just want to keep the car very streetable and maintain a reasonable vacuum level.

I also have a 2400 stall converter in the car and do not want to go higher than that rating.

To answer some of the questions, intake will be a 750 Demon with Vac secondaries. The goal of the car is to have a powerful weekend crusier that has the following criteria:

* Maintains enough vacuum to operate everything
* Capable of highway cruising for an occassional roadtrip
* Over engineered reliability within reason
* excellent power band between idle and 5500rpm
* Award-winning burnouts, on demand

 

GO WITH 190-195 AFRS HEADS AND BE DONE WITH IT :cheers:

 

Have read a bunch of build-ups with 383's and 406's using the AFR 190 or 195
heads, incredible with a Comp Cams hydr roller either their 276HR (224-230 x 503-510) or 282 230-236 x 510-520 with a 750 Demon and RPM air gap and most of them running 1-5/8's long tubes (couple of them tested 1-3/4's and had better & wider torque range with the smaller tubes) getting 425 to nearly 450 torque at 2500 (peak torque just about 500) and peak hp also nearly 500 in the low 5k ranges. See dyno articles on AFR website and on Lingenfelter Racing website. Reportedly fully streetable with full vacuum. Those were with 9.4 to 9.6 cr. Do a search for 383 and 406 buildups, too. I'd LOVE to try one with an
RPM Air Gap and an Accel DFI or FAST system. Recently been researching LT1's to 383 with AFR 190 LT1 heads and just a tad smaller Comp Cams HR with 112 LDA for efi, using GM Perf's dual plane 4bbl intake - a lot like the Perf RPM for (per GM) about 30 ft-lbs more torque (on a 350) than the LT1 intake.
I wrote AFR tech, and they wrote back saying the 383/406 engines w/ the 190 heads and RPM Air Gap with those Comp Cams feel nearly the same in throttle response and acceleration all the way from 2500 to over 5k - superb street engine esp. with an auto and mild stall, even with tall street gears.