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Old 08-06-2017, 01:24 PM   #1
Sawlog
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How much hp gain?

I recently replaced the iron heads on my truck and changed the cam. 350ci
My old heads were 72cc with 1.94intake and 1.60 exhaust. Cam was stock.
My new remanufactured heads have 64cc chambers with new 2.02 and 1.80 valves. The intake and exhaust ports were opened up too. My dad called it gasket matched?
New cam is summit 1102, 204-214 at .50. 421-444 lift.
My question is... is there any way to guess how much of a horse power gain it made?
Thank you
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Old 08-07-2017, 06:58 PM   #2
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Re: How much hp gain?

how does it feel? more power off idle or in the upper RPM ranges?
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Old 08-07-2017, 07:03 PM   #3
Sawlog
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Re: How much hp gain?

Quote:
Originally Posted by tdangle View Post
how does it feel? more power off idle or in the upper RPM ranges?
I would say lower range
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Old 08-07-2017, 07:19 PM   #4
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Re: How much hp gain?

other than a wild guesstimate ..only way to know for sure would be stick it on a dyno
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Old 08-07-2017, 08:57 PM   #5
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Re: How much hp gain?

Go on comp cams site.Look for cam quest.You can build your motor and it will tell you what hp you are at.
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Old 08-07-2017, 09:18 PM   #6
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Re: How much hp gain?

Quote:
Originally Posted by Sawlog View Post
I recently replaced the iron heads on my truck and changed the cam. 350ci
My old heads were 72cc with 1.94intake and 1.60 exhaust. Cam was stock.
My new remanufactured heads have 64cc chambers with new 2.02 and 1.80 valves. The intake and exhaust ports were opened up too. My dad called it gasket matched?
New cam is summit 1102, 204-214 at .50. 421-444 lift.
My question is... is there any way to guess how much of a horse power gain it made?
Thank you
went from 165 to 250 maybe 275 hp
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Old 08-08-2017, 06:40 AM   #7
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Re: How much hp gain?

That Performer cam is bigger than the factory 350 hp cams but I really don't believe it would make 300 hp. I'm with hjewell2 that it is more likely 250-275.
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Old 08-16-2017, 08:58 AM   #8
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Re: How much hp gain?

Camquest is typically generous in their ratings. After all they are trying to sell performance upgrade parts. Anything outside of a calibrated dyno run is just a guess which is essentially what you asked for, I guess ...
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Old 08-17-2017, 06:37 PM   #9
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Re: How much hp gain?

Years ago I had a program called "Desktop Dyno" that had lots of options. It worked pretty well, of course the % change guesses were more useful than the absolute numbers. Not sure if it's still around.
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Old 08-30-2017, 11:59 AM   #10
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Re: How much hp gain?

What type of intake manifold do you have (single plane? or dual plane? type?)...and what type of Carb?
Also, what type of ignition?...HEI?...was the motor in good condition with good compression and in good tune?
All of this has a major bearing on performance in addition to internal mechanical upgrades.

All good
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Old 08-30-2017, 12:34 PM   #11
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Re: How much hp gain?

Another nice reference is the "Engine Masters" youtube show (also on Motor Trend on Demand).

If you're lucky, they have tested parts combinations similar to yours. They try lots of stuff on the dyno.
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Old 08-30-2017, 01:01 PM   #12
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Re: How much hp gain?

Quote:
Originally Posted by Coley View Post
What type of intake manifold do you have (single plane? or dual plane? type?)...and what type of Carb?
Also, what type of ignition?...HEI?...was the motor in good condition with good compression and in good tune?
Yup! So many variables. Was the engine and fuel system tuned to take advantage of the extra potential? There is more to it than just bolting on parts. Need to be tuned to take advantage of the potential there.

Big fan of Engine Masters show but if you pay close attention you hear them mention Steve has run the engine several times off camera tuning it before the Final Pull they usually show. There is a lot of work goes on to find all that HP.
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Old 08-30-2017, 05:18 PM   #13
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Re: How much hp gain?

1.8 exhaust valves...never heard of that size. A gasket match is not porting. Sounds like you used another set of stock iron heads with bigger valves and a 30yr old mild cam that everyone calls the "RV" cam. I'd say you gained 30hp or so.
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Old 08-30-2017, 06:55 PM   #14
Sawlog
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Re: How much hp gain?

Dual plane preformer edlbrock intake with 600 cfm carb. 1.625in long tube headers with 2.5in dual exhaust hei ignition. I did compression test, 135psi on all cylinders. And yes it is tuned pretry good.
1.60 exhaust valve. Sorry.
on paper my compression should of went from 7.7 to 8.5.
It made a world of difference!
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Old 09-01-2017, 12:31 PM   #15
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Re: How much hp gain?

Here is an Engine Masters episode looking at original stock heads vs. Vortec head and cam upgrade:
https://www.youtube.com/watch?v=f7mv...u7srE&index=25

They changed too many things at once, but maybe the tests here will bracket what you have. Your power is probably higher than the baseline, but lower than their max case.
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