Headers too big??

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wilson1970
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Headers too big??

Post by wilson1970 »

I have a set of Hooker Super Comp 1&3/4" headers will they work for the following combo? I know 1&5/8 would be better but the Super Comps are what i have. 355 SBC zero deck, 10.5 compression, .520/.540 lift 236/242@.050. Hydraulic roller, Sportman 11 heads with some port work, stud girdle, Rpm Air Gap intake 750 HP carb. 3200 Converter and 3.73 rear gear. Street engine. Thanks
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Re: Headers too big??

Post by statsystems »

Nope. Not too big. Bought my first set of 1.875 headers in 1984 that I used on a street strip car. I wasn't doing engines at the time, and the moron engine builder made it 8.5:1 even though I asked for 10.5:1.

After many arguments, tuning discussions with header guys on the phone and with the engine builder bitching, I swapped out the 1.75 headers for the 1.875 headers.

By the end of the day I was almost .15 quicker. I forget the MPH but it was faster.

Need less to say, that dude was fired and I started doing my own shit.
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Re: Headers too big??

Post by cgarb »

I agree too. In my racing experience I have found the same to be true. I was told the 1.875 tube headers were too big for my 355. The people that said that it would kill the torque could not explain the 1.40 and 1.38 60fts I was getting though. 355 in a 3300lbs Buick Skylark footbraking. Maybe it just was a good combo for me, but I have no complaints. I bought the larger tubes looking to the future for room to grow to a larger engine.
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Re: Headers too big??

Post by lefty o »

just my wild opinion form some experience, but 1 5/8 on a 350 run out of gas at about 425hp. imo the 1 3/4" is a better choice.
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Re: Headers too big??

Post by groberts101 »

Ok, I'll go against the grain here and be the odd man out.

IMHO, the cam's not that big and the dual plane manifold will give up before those 1.75's reach their full potential. What some "street engine" guys fail to recognize is that the collector size is often more critical than the primary size to capitalize on the cam/inductions sweet spot. 3" collector would be about max size and 3.5" is way too big for that combo.

If it were my ride I'd crutch the primary size for that SPECIFIC COMBO OF PARTS with a merge collector and choke somewheres in the 2. 375" range. Won't hurt peak power one bit and the motor will feel bigger under peak torque. I bet it hits that converter harder too. That's exactly what my last 383 did with similar combo of parts.
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Re: Headers too big??

Post by cjperformance »

groberts101 wrote: Wed Mar 14, 2018 11:31 pm Ok, I'll go against the grain here and be the odd man out.

IMHO, the cam's not that big and the dual plane manifold will give up before those 1.75's reach their full potential. What some "street engine" guys fail to recognize is that the collector size is often more critical than the primary size to capitalize on the cam/inductions sweet spot. 3" collector would be about max size and 3.5" is way too big for that combo.

If it were my ride I'd crutch the primary size for that SPECIFIC COMBO OF PARTS with a merge collector and choke somewheres in the 2. 375" range. Won't hurt peak power one bit and the motor will feel bigger under peak torque. I bet it hits that converter harder too. That's exactly what my last 383 did with similar combo of parts.
X2 ^^ i agree
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Re: Headers too big??

Post by Geoff2 »

X3
BILL-C
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Re: Headers too big??

Post by BILL-C »

I have a set of 1.75 x32long primary x 3 " collector dyno headers that always perform very well with combinations like yours. I would expect that hooker number to have a 3" collector also.
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Re: Headers too big??

Post by cjperformance »

BILL-C wrote: Thu Mar 15, 2018 6:45 am I have a set of 1.75 x32long primary x 3 " collector dyno headers that always perform very well with combinations like yours. I would expect that hooker number to have a 3" collector also.
With a full street exhaust system behind them?
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Re: Headers too big??

Post by wilson1970 »

The headers have 3" collectors. I will have full 3" exhaust with flowmaster 3 chambers and turndowns behind rear tires. Also, H pipe or X pipe? Whats the opinion?
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Re: Headers too big??

Post by plovett »

I miss Big Joe telling us our headers and cams are too small. Well I know he said that about cams. I think headers, too.

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Re: Headers too big??

Post by cjperformance »

wilson1970 wrote: Thu Mar 15, 2018 7:06 am The headers have 3" collectors. I will have full 3" exhaust with flowmaster 3 chambers and turndowns behind rear tires. Also, H pipe or X pipe? Whats the opinion?
All other sizing aside, i like a H pipe in the same diameter as the collector right at correct collector length.
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Re: Headers too big??

Post by Truckedup »

From my often not too bright point of view...Since there is some disagreement here whick I assume is from expereince, maybe pipe diameter isn't a big factor ...OP says it's a street engine..Will a 1-5/8 pipe with proper size collectors make more power at reasonable RPM levels? Or you drilling around the streets at 6000 RPM all the time?
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wilson1970
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Re: Headers too big??

Post by wilson1970 »

Thanks for the responses. The reason why I ask is I have these headers from a previous project. Can i get away with these or will I regret using them. These thing were quite expensive. And yes this is a street engine looking for power to be done around 6200.
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Re: Headers too big??

Post by groberts101 »

lol.. the motor will still run and you'll be fine. I'd figure low to midrange ft/lb losses somewhere's in the 8-12 range but you'll never know the difference once it comes up on the cam. That's assuming a 3" collector size though.. 3 1/2" will be a turd and not hit the converter as hard and likely sofetn the stall speed a little bit too.
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