Headers Killin me?
 

Just wanting some fresh opinions from my fellow racers here instead of all the BS from the guys over @ YELLOWBULETT. I built this motor a little over a year ago, first time out it ran 7.89. Mabey 30 passes later after tuning, cam, roller rocker to 1.6, eddy vic. jr p&p, spiers racing 215cc heads, and more tuning it has only bested ar 7.82? Could it be possible that my old 1-1/2 primary tube headers are holding me back, or do you guys see other problems in my sig.?
thanks,
skeeterbug

Re: Headers Killin me?
 

I'd think with an aftermarket convertor and all that jazz, you'd cut a better 60ft. Are you spinning, bogging or anything like that?

From the mechanical standpoint, you do have a lot of air coming in, so increasing your header size couldn't hurt, but I don't know that its your only bottleneck.

I would think based on your setup, that the truck makes more power at the top end with that cam, higher rockers and those heads and big ported manifold. Since your running in the 1/8th, you may never see some of the power your engine makes in the higher rpm's.

What was your dyno before and after?

Re: Headers Killin me?
 

It leaves fairly hard but that doesnt mean its not spinning some i need to get my wife to video my launch i guess. If its any help to you all I shift at 6000 rpm, but with the 3.73 i dont hit D(high gear) till about 50 ft before the stripes. i have an add in the WTB section for a 4.56 r&p. How much do you all think that would help?

Re: Headers Killin me?
 

Is this a street truck or a race truck?
At what rpm does the motor make peak tq?
How much tq does it make?
At what rpm does it make peak hp?
How much hp does it make?
Where are you shifting?
What gear/rpm are you going through the 1/8 mile trap at?
What does the truck weigh?
What size tire is on it?

If it is a race truck, I'm guessing the verter is too small, it should be at or slightly after peak tq.
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Re: Headers Killin me?
 

Well as many others it started as a street/strip build now it see's the strip more than the street. I thought i put earlier never dynoed but i see i did not, sorry therefore i cannot answer many of your questions. shifting at 6000, low side of high gear at the stripes, about 3800 lbs, and 28 x 11.5. Forgive all the vauge information but dyno's are sparse around here and very high for my blood, wish i had more.

Re: Headers Killin me?
 

I will say that I think the right converter is worth more than the gear change.

Example.. I went from a 3600 verter cutting 1.89 60's with a 26" tall tire and 3.73's, to cutting 1.67 60's with the same gear but a 30" tire and a 4500 rpm verter.. The tire change was a pretty drastic gear change, but I picked up .22 in th 60'... It was like going to a 3.23 gear with the 26"tire.

3.73 with 26" @ 6k = 124mph
3.73 with 30" @ 6k = 143mph
3.23 with 26" @ 6k = 143mph

Later I did the gear change. Same tire height 30" but went from a 3.73 to a 4.56. I also took some weight out of the truck. Dead hook consistent 1.60's with a best of 1.59.. Only went down .08 at best.

This recent outing, I was cutting 1.60's. Took my tailgate off which weighs 125lbs, and with No other changes cut a mid 1.5. So how much of the 3.73 to 4.56 change was weight vs gear?
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Re: Headers Killin me?
 

1.5 primaries are just about too small for a stock 350. Most sbc headers are 1 5/8's. With your setup I would be running 1 3/4 primaries into a 3 inch collector.Going to a larger tube header is going to help more on the top end than on take off. I definately agree on the converter as well. What brand is the converter? Can you actually launch at 3000? You definately get what you pay for when it comes to a torque converter.

Re: Headers Killin me?
 

B & M converter, i can stall up to 2450 rpm max on footbrake before the tires break free.

Re: Headers Killin me?
 

I was afraid you were going to say that. Spend some cash and buy a quality torque converter. Ati,Bte,hughes,Yank etc. Off the shelf converters arent the greatest in the first place. B&M stuff is of lower quality than most other off the shelf converters. They rarely hit there target stall. They aren't known for being the strongest converters either.

Re: Headers Killin me?
 

I usually stay out of these threads , but this combo is so close to mine that i have to chime in . 6000 is short shifting . 6700 it is laying down with this cam . The header size is too small for the 215 head @1.5 primary . I have a 3800-4200 BTE nitrous converter with almost the same combo ( 210 heads and touch less compression wise ) mine only footbrakes to 2200 . Have you tried getting a running start at the converter ? Stage it at 1000-1100 and deck it . The added fuel from the pump shot , plus flashing the converter @3800 #'s should move the stall speed up . I also agree it needs a converter . Does it dead hook now ? If so try a set of 26" rear tires for an experiment .

Re: Headers Killin me?
 

It doesnt dead hook, it actually seems to spin some at times. Silly question but what would the difference between 28" dia. vs 26" dia. other than the ratio reduction?

Re: Headers Killin me?
 

Just that, similar gearing between:

28" - 4.10
26" - 3.73

Hotrod is simply suggesting a tire change before the gear change. It is about the same total price, and is easily reversible if the outcome is not what you wanted.

What tire are you using?
What is your burn out process?

I find with drag radials, they like to be hot. I set my line lock, go wide open, shift the second, hold it there for a good couple seconds and roll out spinning the tires until it lunges you forward. You'll feel when it is ready to hook.
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Re: Headers Killin me?
 

28 X 11.50 ET Streets on 15 X10 Rallies, burnout process is exactly as yours minus the line lock.

Re: Headers Killin me?