5 psi boost
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From: Kentucky
5 psi boost
Does anyone know how much HP increase an otherwise stock 86 with alum 128 heads would be with a 5 psi boost? I know 5 psi isn't a lot, but it is better atmospheric pressure and I'm thinking about trying to design this system on my own.
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From: Kentucky
Re: 5 psi boost (fullboogie)
I know that there is a lot of engineering into superchargers and turbos, but if I can design a belt driven system to increase psi even just a small bit it would be better than just letting the engine suck the air in. As long as I can get the "fan" to flow air faster than what would normally come in thru driving I think it would work. The little bit of HP that it would take to spin the fan might be able to be exchanged by a smaller pulley on the power steering pump/AC.
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From: Kentucky
Re: 5 psi boost (fullboogie)
I have a book called Maximum Boost, but the numbers that it gives for a naturally aspirated engine is higher than what GM rates the HP for my car and that is why I have the question posted. The book also says that almost every car can handle up to a 5psi boost without additional mods and this is where lights go off in my mind. If I could design a mild compressor I could potentially help other L98 folks greatly improve our airflow and HP for less money than a SR or Mini.
[Modified by castivers, 12:45 AM 9/24/2002]
[Modified by castivers, 12:45 AM 9/24/2002]
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From: Exit 89 GSP,Lakewood,NJ The Land Of Mojo
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Re: 5 psi boost (castivers)
I have the same book, but from talking to some that are in the business, the general estimate seems to be 18-20 hp per lb of boost.
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From: Kentucky
Re: 5 psi boost (Mr Mojo)
That helps a lot. I was guessing that a belt driven compressor might take 10 - 15 HP to run and a smaller pulley on AC might help to cancel some of this out. Now if I can come up with the rest of it for a reasonalble price and end up with a 4 -5 psi boost I could be looking at 72 - 90 HP gain.
8th Gear
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From: Dryden NY
Re: 5 psi boost (castivers)
I've been thinking along similar lines. All of the photos I see of vintage race cars with blowers appear to be homebuilt. Seems to me we could do the same for, as you suggest, a modest boost increase. I'd be very interested to know how this goes for you. Keep me in the loop if it's not too much trouble. Any thoughts about how you'd measure the boost pressure?
-David H. :yesnod:
-David H. :yesnod:
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From: Silicon Valley Kalifornia
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From: Surrey BC
Re: 5 psi boost (fullboogie)
How do you plan on enriching the fuel circuit? You've got to add more fuel along with more air (boost), you know.
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Re: 5 psi boost (Chief Muktar)
I think typical ads rate something like 40%hp gain from 6psi boost; but I don't recall if that's with an intercooler.
This comes to something like 6-7% gain per psi boost or 33% at 5psi; about 80hp for a stock L98.
Since we can get such gains from bolt on mods you may be able to handle it with only an AFPR at 50-55psi.
That raises an interesting point, on the early '90s T-Bird SuperCoupe, you could dial in the desired amount of boolt. I assume they just "dumped" some of the air flow, but how to modulate the fuel...hmm. I guess the MAF would handle that.
This comes to something like 6-7% gain per psi boost or 33% at 5psi; about 80hp for a stock L98.
Since we can get such gains from bolt on mods you may be able to handle it with only an AFPR at 50-55psi.
That raises an interesting point, on the early '90s T-Bird SuperCoupe, you could dial in the desired amount of boolt. I assume they just "dumped" some of the air flow, but how to modulate the fuel...hmm. I guess the MAF would handle that.
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From: Houston TX
Re: 5 psi boost (65Z01)
65Z01-
The fuel enrichment circuit on the Bird was boost-referenced, so that it raised fuel pressure x-psi for every pound of boost present in the intake. Kinda like the fuel management units in the modern blower kits.
The fuel enrichment circuit on the Bird was boost-referenced, so that it raised fuel pressure x-psi for every pound of boost present in the intake. Kinda like the fuel management units in the modern blower kits.
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Re: 5 psi boost (fullboogie)
Ah, so it took ECM control. I can't recall if her '91 SC T- Bird had a MAF or not.
So, it sounds like a MAF and an AFPR cannot get the fuel/air right with a SC. Or do the kits have outside fuel pressure control primarily for cars without a MAF and for installations where the amount of boost can be varried during engine operation.
[Modified by 65Z01, 2:57 PM 9/24/2002]
So, it sounds like a MAF and an AFPR cannot get the fuel/air right with a SC. Or do the kits have outside fuel pressure control primarily for cars without a MAF and for installations where the amount of boost can be varried during engine operation.
[Modified by 65Z01, 2:57 PM 9/24/2002]
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From: Kentucky
Re: 5 psi boost (65Z01)
I haven't had a lot of time to try and work on anything today except moving. I've got a few ideas in my head and when I have a chance I'm going to try and fab something up. I have a couple of sources to check about the fuel psi, but you guys have put me in the right direction.
