How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

If I want to put a Whipple or Procharger on a 9.5cr 572 carbed engine, how much boost can I run on pump gas? I'm thinkin 3-4#'s.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

4 lbs should be no problem. Whipples kits run 5-6 intercooled and that is on 8.75 compression. If it is carbed just richen it up a bit :D

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

What about AV gas or AV and 91 mix?

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

faster,

what kind of boat you looking at ?

Don

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

This is good info. I am building my motors now, and I am building them with the option to bold on some huffers, maybe next year.
My CR is 9.6:1 454 with Canfield aluminum heads and full roller valve train and head studs already installed.
My engine shop suggested that I have the heads o-ring'd for the head gaskets if I want to run the huffers, but the head manufacturer suggests against o-ringing the heads.
Do you think I can run 3 - 4 lbs. boost safely on 93 octane?
What about head gaskets?

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

cometic multilayer head gaskets are unbelievable.

Mike

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

What's up Chromecat Don,
I ordered a Superboat Y2k 30'er. It was difficult for mr to give up the American Offshore but I wanted a cabin for overnighters and still have a fast boat.
Tom

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

good luck...
Don

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

DO NOT USE AV GAS!!!!

DO NOT USE AV GAS!!!!

DO NOT USE AV GAS!!!

Aviation fuel is engineered to run at a lower RPM than standard, or racing gasoline. Most aircraft run at about 3400 RPM Max. It is also designed to run in the thinner atmosphere of altitude. Mixing it with unleaded can actually hurt your performance. I’ve seen many people have problems, and hurt there engines trying to run AV Gas. I have personally done it without any problem, but you have to richen up your mixture to be safe, and then add some lubricants. You’re better off building the engine to run on 89 Octane, and use 93, or add in a little true race fuel.


As far as how much boost you can run with that much compression there are too many variables to answer it with a definitively. Chamber design, Cam selection, porting, headers, head material, ignition timing, and etc. will all play factors. I’ve seen people run as much as 8 lbs of boost on top of 9.5:1 compression. The rest of the engine was built around these factors. Normal cruising however was limited to 4 lbs of boost.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

I don't want to pirate this thread, but I think that's what we are looking for. If we have 9.6 (or in his case, 9.25) CR, what does it take to run huffers on pump gas?
I have Canfield 310 heads (as cast) 119CC chambers and Revolution Marine exhaust manifolds, along with everything else noted above.
Can I run huffers? And what amount of boost is safe? Would and EGT Sensor be mandatory in this situation? Do I have to run chillers? Is it a must that I install a bigger gas tank (that's obvious :D )

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

I am not an engine builder but I was told by Mike D'Anabell(spelling) that 100LL av fuel is the next best thing to raceing fuel.Much better than 93 pump fuel. He told me that the lead that was in it, is a great lubricate and that the valves would love it.
I had 598's with 8.75 c/r and ran 9#s of boost. This was actually set up on the dyno to run 91 oct, but AV fuel was easily available so that is what I ran most of time, I did run some straight 93 at times though. Just my experineces. Oh yea, I was turning about 6200RPM.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

This is news to me RumRunner. I ran AV in my ProCharged 8.5cr 7.5#'s boost for a couple years. I did'nt have any problems but maybe I was lucky. I know 100's of people on Havasu that fill up weekly with AV. Some use a little Mystery oil in it and others don't. Thanks

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

The compression ratio vs. boost question comes up a lot because it is a pain to change pistons. But if you were thinking about changing heads and currently have 120cc chambers, many aftermarket aluminum heads can be purchased with 140cc, which is a better way anyhow.

Adding a blower and then restricting yourself to low boost is kind of a poor return on "investment". You might only see a 25% gain, when changing to the proper compression ratio and increasing boost will gain 50% or more depending on blower eff, intercooler eff etc.

Still, I believe everyone should have a blower, so go for it and change the compression at your next rebuild. :D

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

My engine is a 572ci 700Hp 9.5cr Canfield heads Lightning headers. That's all I would want is 175-200more Hp.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

"D'Anniballe".....


This information comes from the feedback we've gotten from customers, and from lab information from the fuel manufactures themselves. I know of one guy that ran his boat here on the east coast fine, went to Havasu, put in AV Gas, and burnt it up... Not to say this will always be the case, but I'd be very careful with it. We see street / strip guys hurting engines on a regular basis. I've run both ways, it all depends upon how good you are tuning.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

"I only want 175-200 HP more..." :D

Remember the Hot Rodder's Creed...if more is better, then too much is just right! :evilb:

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

As stated earlier, I'm not an engine builder just a parrot. I do however highly respect his opinion,as do many. I just hope he is correct. I only run the AV fuel for insurance.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

I think the biggest issue with running AV gas is the specific gravity of the fuel. If you tune your motor for race gas or 93 oct. pump fuel, it has a pretty high specific gravity of usually around .750 and then put in AV gas with specific gravity of lets say .680 you motor will be lean and it will probably melt over a long WO run.
Always be aware of the specific gravity of the fuel you tune with because even if you change brands of fuel with the same octane there can be a big difference in specific gravity. If you look at guys that run big NOS this is one of the most important facts they look at because a little difference means disaster even with the same octane.
Bottom line if you tune with AV gas or blend with it make sure you always do it the same. I have personally never had problems with AV gas if I tuned it with it first.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

I think that's the key to it. I always run my boats a little fat. Maybe that's why I had 350hrs on a ProCharged 454mag bottom end. All I did was change heads, intake , and carb, 7.5#s boost. Still running strong.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

What difference does the specific gravity make if the fuel is pressurized with a regulator? IE you make the same PSI with AV or 93?

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

This has nothing to do with fuel pressure.
The higher the specific gravity the fuel is denser therefor the fuel is packed tighter in the same amount of space which makes it weigh more.
Air/fuel ratio is measured in weight therefor a 12/1 ratio will be 12Ibs of air to 1Ib of fuel. So if your carb pulled out the same amount of fuel in volume and it had a lower specific gravity there would be less fuel for the air that passed the booster. Then the only way to correct this would be to add heavier fuel or increase the jet size.
It is important to know your specific gravity when tuning because .01 difference in specific gravity usually means 1 jet size difference and if your already on the lean side good luck.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

I would suggest you follow your thoughts. I did a 572 with 9.2cr, ran 4.5 lbs with just 93 fuel and its still living. Watch the timing and keep the heads cool. A 26 Velocity went from 86 to 98 GPS. Had to go up quite a few jets to get the plugs looking good from a normal blower carb setup. He still stops at every fuel station, but gets there quick.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

It's not all just the Specific gravity of the fuel, there are other factors.

That being said we'll look at Nobody's example. As fuel gets hotter it looses some of its high end additives, and the Specific gravity gets lower. If you had your engine calibrated to run with a fuel at .750 SG, and it dropped to .680 SG. That is a change of about 9%. That change moves with the flow area of a fuel jet. Bottom line meaning if your carburetor had # 90 main jets in it with fuel at .750, and the fuel got to .680 you'd have to go up to a #93 or #94 main jet. Big change!!!

Rich as safer!!!

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

Does this hold true for regular race gas...this got started talking about AV gas.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

Very much so.
When you buy or look at the web sites that sell or manufacture the fuel they should list the specific gravity for the model number fuel they sell. If they don't all you have to do is call and ask them what it is.
Here are some examples:
Sunoco-111---------.725
Sunoco-112---------.715
VP RED--------------.742
VP C12--------------.710
VP C14--------------.690
VP C16--------------.730
AV GAS between---.650 and .700
93 pump fuel average .750

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

i think i would go with rum runner on this.... :cool: :cool:

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

PM Bobl...
He is currently working with Dustin on a 565 with 9.4:1. Appears the cam is a big savior here also. He can give you the details.

Re: How Much Intercooled Boost Can Be Run On 9.5 Comp Ratio
 

:drink: