aussiemart

Hi guys,, i need to make 500hp in my circuit race car with a 30 thou 351c, im not wanting to rev it past about 6600 rpm and was wondering if the 185cc heads would be better suited to road racing for there torque production in the mid range area for corner exits,,but im not sure if i could get 500 hp in this rev range with the 185cc heads.

So what i really need is the most power i can get from about 3000 to 6500, has anyone had any experiance with either of these heads and a manual car,, and what cam and compression would you advise,, would be running on 98 octane premium fuel,,would try and fit the chi manifold under the bonnet and the exhuast would be optimized.

Cheers Marty.

__________________
Feed my will to feel this moment urging me to cross the line..
We'll ride the spiral to the end and may just go where no one's been...
M.J.Keenan

balinor

The 185cc heads will give you what you want Marty & the torque should be phenomenal.

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"There is only Bathurst the rest is just waiting"......

TruBlu351

Look around the CHI website with some 351's with the 185's. Here's a dyno run on a 366 clevor.

http://www.chiheads.com/dynotest_02.html

Here's another..........

http://www.chiheads.com/dynotest_01.html

It gives you their cam size and setup so you could compare that to yours.

Give John a call at CHI (details on website). He'll have all the answers for you. Very helpful and informative.

Brenx will be up soon...........he has the 218's on a 351 and hopefully some new dyno results soon

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XE Falcon
393 Tremec TKO 9"

brenx

Cam choice will play into this due to your specific rpm. It's best to speak with John @ CHI and get a custom ground cam to suit your needs. With my next build I am looking @ getting a custom cam via John. It should have been this year but damn C4's don't like me.

I don't think the 218cc ones will make that power in the rpm range you require. My last dyno was max power @ 6600rpm limited by what we think was valve springs. I'm looking at doing max power around 7000rpm next time. I should know within 4-8 weeks. I'm dropping my car off to my dyno tuner for some custom work and a dyno tune next week.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

aussiemart

Thanks alot guys,,,Think your right brenden a custom cam would be the way to go,,probly need a rollor id say,,being an engine thats reved all day i was hoping to make the maximum power with the least amount of rpm to try and keep it all together for a while:-)

That second link you posted true blue,, sounds like too mutch hpower and torque for sutch a small cam,,what do you guys think

.http://www.chiheads.com/dynotest_01.html

Thanks so mutch guys,,
Marty

__________________
Feed my will to feel this moment urging me to cross the line..
We'll ride the spiral to the end and may just go where no one's been...
M.J.Keenan

crochunter

Yes at CHI website dont beleive everything you read.

brenx

It has no BS. What people tend to miss is the cam spec. I do my own testing computer dyno's (desktop dyno) aren't always correct. Results speak for themselves. As a further note most of those test figures are from customer engines. Not test mules. I'd love to get mine on an engine dyno. The downfall? It's a pain in the butt to transport the engine. I'd have to buy a ute or trailer. So I don't bother chassis dyno will just have to do.

My testing so far is:

2V heads engine same spec 227rwkw
218cc heads engine same spec slight increase in compression 279rwkw
I've now bolted on the CHI manifold and will have test figures soon enough

Summary : 50rwkw gain bolt on, so far. Who can argue with that

[edit]As a side note look @ xbwgns engine 238@50 (Crane F238) it does 252rwkw. It's a smaller cam than mine. It's a matter of what cam works better with the heads.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

brenx

playing spot the obvious here. Look how little the cam duration @ 50 is separated. As this is where power can be found Off the shelf clevo cams tends to have 8-12 deg difference between inlet and exhaust. Mine has no sep mines 248@50 in/ex. Which seems to suit the heads unlike the cast irons which it didn't suit.

Brenden

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XB Fairmont (street car) 11.07@123.02mph.

aussiemart

yep i know about the @ 50 seperation should be closer than whats the norm for clevos but it still is a mighty fine effort,, i mean thats only about 228 intake duration in a hydro cam if you go by the take of ten degress to convert solid to hydro theory

__________________
Feed my will to feel this moment urging me to cross the line..
We'll ride the spiral to the end and may just go where no one's been...
M.J.Keenan