Squeezing more HP out of a 434

[ralph85]

My nephew has gotten into running a 10.0 index class. The problem is in the summer heat, he can't run the number. It's due for a freshen up this winter and I'd like some ideas on where to find the additional HP. Car has run a best of 9.90 @ 136, but in mid-summer it's usually in the 10.20s. short times range from low 1.3s to low 1.4s depending on weather and track conditions.

The car is 3300# w/driver, TH 350 w/brake, ATI 8" converter (flashing to 5-5.5K), 4.11 gears and 28" tires. The engine combo is a Dart block 434 with a fairly heavy rotating assembly. Heads are Brodix M2 Track 1s with some minor cleanup (230cc intake), 59 cc chambers for 12.5:1 CR. Intake is a port matched super victor with a 4500 flange, converted to EFI with a 2000 cfm TB on top. Cam is a crower 260/272 @ 50 on a 106 LSA installed straight up with about .710 net lift at the valve. Headers are 1 3/4 to 3" pipes and mufflers (required).

Would like to hear some ideas to knock off 2-3 tenths. We're NOT looking to go 18 deg, shaft mouted rockers or power adders. We're already tight on PV clearance so moving the cam or increasing valve lift would probably require cutting the pistons (not out of the question). I've got some ideas, but would like to hear from the experts. Thanks!

BTW, i read the 12 page thread on the "disappointing power from 434" and many of you feel it's easy to get over 700hp out one of these and i don't think we're there yet.

[bigjoe1]

This is right up my alley. You did not say what RPM you shift or at the finish line.Do you have a hood scoop that works ??What brand of camshaft are you now using ??How much do you want to spend ??
JOE SHERMAN RACING ENGINES

[Bucky1]

What Joe said. What is that finish line rpm? Then we can talk gear maybe. How about a diet for the car? May be the cheapest e.t. you will buy. Knock out a couple hundred pounds and you are there.

[ralph85]

Shifting and going thru at about 7200-7300. We have a working cowl hood, but clearance above the TB is limited....approx 2 1/2" in front to 3 1/2" in the rear. Cowl is about 18" wide and the TB is reasonably sealed to the hood. Current cam is a Crower grind. Not exactly sure on my nephew's budget, but i'd say $2500-3500.

We've already knocked a bunch of weight out of the car, but my nephew is close to 300#. It would be hard to cut substantially more weight out without really hacking it up......not sure if he'd be into that. We WILL probably cut about 50# out this winter and relocate another 25.

[Fatman]

Camshaft change would be quite a cheap start. I think a motor like that turning 7000+ could like quite a bit more intake duration even if you don't increase the lift. I'd look at increasing camshaft duration. Watch your pv clearance. If you have to cut some, your losing compression as well. As for the size of the cam, i'd stay a bit on the conservative side if you do not increase the compression ratio. Make sure you have enough cylinder head to support the rpm you want.

Can you increase your compression with some new pistons?

[369dragster]

If the exhaust valves are the ones that come from Brodix I would change them to a tulip style valve,rather than the nail style.I picked up almost a tenth switching.I also ran a much bigger camshaft,but my motor was in a dragster.282@50 int. and 288@50 exh. with .715 lift.My motor made about 730 with a toilet on it. Ken

[wheelsup]

If you run gas, switch to alc and your done.

[randy331]

Would like to hear some ideas to knock off 2-3 tenths.
Heads are Brodix M2 Track 1s with some minor cleanup (230cc intake),

If the heads have just been cleaned up, I'd start with the heads. Get them ported by a competent cylinder head ported.

[highVE]

Those heads (gegardless) of them being cncd, do repsond well to porting. especially at the pushrod pinch.

I did a set last spring, and have a set to do over the winter. The air speed is through the roof at that critical pinch, and crossection is way to small for a 434 turning 7000rpms

Mike Theroux
www.mikesportingservice.com

[Fatman]

Those heads (gegardless) of them being cncd, do repsond well to porting. especially at the pushrod pinch.

I did a set last spring, and have a set to do over the winter. The air speed is through the roof at that critical pinch, and crossection is way to small for a 434 turning 7000rpms

Mike Theroux
www.mikesportingservice.com

Mike
Do you know what the csa is of these through the p/rod pinch?

I thought that at 230cc they would have been big enough to support a peak HP rpm of about 6500rpm on 434.

[ralph85]

So far a couple of votes for more cam, a couple more for addtional head work and one for alcohol. Bigjoe & Bucky haven't checked back in yet. Please keep the suggestions coming.

Wheels, do you have any specific examples where the switch from gas yielded 2 tenths with no other changes in a similar scenario?

VE, do you know what the CSA is at the pinch point on these heads? These are the CNC versions and the intakes have been cleaned up a little. They flow pretty close to as advertized (over 300 cfm above .500). The valves are original as supplied by Brodix.

[automotive breath]

I agree you could use more duration. We just assembled a 434 short block
from shafiroff with home ported 215 intake runner Dart Pro 1 heads.
Mr. John @ Bullet sent a CHS302/310-06R; 271/279 @050, .4267" lobe
with 1.6 rocker on the intake.

First outing last night went 9.60 @ 137 2800 LB Camaro on a mild tune,
5500 stall foot brake. Will know more this weekend.

[Fatman]

I would think that either brodix or m2 could supply you with the port CSA information.

Does anybody feel this motor could use larger headers?
Is 1 3/4 into 3" enough.

[TOP38]

Ralph

How about your car! Loosing 3 plus tenths from good air to bad is too much so some of your ET loss is from traction. This also shows in your 60's which is a tenth. Work on getting your car to work better especially in the heat. As for your cam, it's certainly small for the cubes,, if you change that you may need to change the stall on the converter to match the cam. 5000 stall also sounds a bit tight now. Switching to alky will also reduce your et loss in the heat. But if you have traction issues now, alky could make matters worse as torque will increase and could cause more traction loss...

[ralph85]

Fatman.....one vote on the exhaust ( i was waiting for someone to comment on the headers)

Top, yes we do have some traction issues that will be addressed, but my car dead hooks consistently and my ETs will vary over 4 tenths across the seasons and my 60s will vary almost a tenth. DA here typically varies 4000 feet from early spring to mid-summer to late fall.

Thanks for the suggestions everyone......Others? BigJoe/Bucky?