compression
compression what will 1 compression point make for horse?
like if i have 9:1 and i went to 10:1 or backwards. what will that charge.
i no i can run more boost with the 9. but level boost out. except for there being boost
18psi on 9:1
compared to
18psi on 10:1
thanks
like if i have 9:1 and i went to 10:1 or backwards. what will that charge.
i no i can run more boost with the 9. but level boost out. except for there being boost
18psi on 9:1
compared to
18psi on 10:1
thanks
http://www.musclemustangfastfords.co...tio/index.html
Two Ford 4.6L engines tested N/A and with a Kenne Bell, one at 8.1:1 and the other at 10.1:1. It's not exactly what you're looking for since the boost isn't exactly the same, but it's close.
The number I came up with is ½% for 1 point in compression, but don't hold me to it!
Two Ford 4.6L engines tested N/A and with a Kenne Bell, one at 8.1:1 and the other at 10.1:1. It's not exactly what you're looking for since the boost isn't exactly the same, but it's close.
The 10.1:1-compression 4.6L produced 401 hp and 389 lb-ft of torque, where the 8.1:1-compression 4.6L produced just 365 hp and 368 lb-ft of torque ... The numbers from our high-compression motor [with a] Kenne Bell supercharger upped the power output to 600 hp at 9.3 psi. ...the low-compression version equipped with the Kenne Bell ... at ... 8.7 psi ... produced only 533 hp.
Last edited by ls1greg; Mar 26, 2009 at 09:00 AM.
boost tends to equalize that difference. The big concern is the added chance of detonation with the higher ratio. A bit more advance can be applied with the lower ratio as well. Why increase the chance of damage for a few more hp?
More compression give more power but boost can make more power than compression increases. Still more powerful an engine is to start with then just means turbos will max out at lower boost and should have more area under the curve? .So 10 to 1 might give 800rwhp at 15 while 8. 1 might need 20 to do it. Engine cubic inch does pretty much same thing. As do better flowing heads and cam and all that .Just let you hit your peak potential at lower boost levels. And remember you are not always in boost. So more power off can't hurt either especially in a street car that spends most of its time off boost. Trust me you won't be in boost much in daily driving or you will be in Jail!
guys generally like the higher compression for other reasons..offboost and there is some debate if higher spools up the turbos faster.
I usually here 8.5 or so for track, 9.0 as nice ratio for no alc injection and 9.5 like mine if you are going to run alc injection which I am.
e85 could easily run 10 to 1 but e85 is not everywhere at least not where I live.if fact its nowhere up here..4 pumps in the whole country.
So might be a reason to go down a bit to 9.5 maybe.
I think my 91 talon is 7.5 but my 97 is 8.8 with the pistons I put in .Some guys go 9 to 1 and again on alc injection still run high boost . I think its more like 5 per cent per half point.
On the afr website there are a couple of thousand hp twin turbo builds. At least one of them runs like 9.5 I think it was. They also ran fast intakes..the one had sheetmetal but then said think fast gave better powerband.
You can find them under mag articles on the site.
guys generally like the higher compression for other reasons..offboost and there is some debate if higher spools up the turbos faster.
I usually here 8.5 or so for track, 9.0 as nice ratio for no alc injection and 9.5 like mine if you are going to run alc injection which I am.
e85 could easily run 10 to 1 but e85 is not everywhere at least not where I live.if fact its nowhere up here..4 pumps in the whole country.
So might be a reason to go down a bit to 9.5 maybe.
I think my 91 talon is 7.5 but my 97 is 8.8 with the pistons I put in .Some guys go 9 to 1 and again on alc injection still run high boost . I think its more like 5 per cent per half point.
On the afr website there are a couple of thousand hp twin turbo builds. At least one of them runs like 9.5 I think it was. They also ran fast intakes..the one had sheetmetal but then said think fast gave better powerband.
You can find them under mag articles on the site.
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TECH Resident
Joined: Dec 2008
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It will be hard to run 18 psi with 10:1.
Assuming you run race gas or e85, 10:1 will net more power.
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Verdad Gallardo ok reason i am asking. motor isnt together yet. but i just reliesed that i was sold the wrong pistons. the ones i wanted should of put me at just about 9.8 to 1 and i the ones i was sold puts me at 8.9 to one.
and i already have all this **** balanced. is it worth switching?
and i already have all this **** balanced. is it worth switching?
I run e85 and about 10.5-1 with my setup and it helps alot for making boost. i could see 10 psi at 3300 with the 346 ci and a S88 with 1.32 ex and it was rising like a rocket but dyno could not hold the load so more testing to come.
