Max boost for stock internal engine?

kenewagner

kenewagner

Registered User
Title saids it all. What would the max boost be for stock heads and cam? Considering menthol injection and supporting bolt on mods.

Ken
 
First tune,daily driver 15 to 16lbs max boost for street.

Second tune
Max boost would be just before you start detonation. And you
would need to pull timing or go with smaller pully to run pump gas.
And add head gaskets Left hand 9262PT , right hand 9263PT.
These are fel-pro COATED MLS head gaskets. I think that
these coated gasket resist shifting or head lifting better than
the regular MLS gaskets used on 4.0 trucks. The numbers
above are 1999 stang gaskets numbers If I remember right.

Third tune .Add The Snow system to tune.

I do not have boost numbers, because I am running a stock boost
gauge with stock motor. Max boost as far as blower pulley overdrive
size for my stock motor. Was 20% with 90 octain gas, detonation started.
And I lifted the drivers side head at around 6000 rpm burnout.
I have had no problems with head lift, since I upgraded to the 99 stang
Coated MLS gaskets.

Randy
 
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Randy N Connie said:
First tune,daily driver 15 to 16lbs max boost for street.

Second tune
Max boost would be just before you start detonation. And you
would need to pull timing or go with smaller pully to run pump gas.
And add head gaskets Left hand 9262PT , right hand 9263PT.
These are fel-pro COATED MLS head gaskets. I think that
these coated gasket resist shifting or head lifting better than
the regular MLS gaskets used on 4.0 trucks. The numbers
above are 1999 stang gaskets numbers If I remember right.

Third tune .Add The Snow system to tune.

I do not have boost numbers, because I am running a stock boost
gauge with stock motor. Max boost as far as blower pulley overdrive
size for my stock motor. Was 20% with 90 octain gas, detonation started.
And I lifted the drivers side head at around 6000 rpm burnout.
I have had no problems with head lift, since I upgraded to the 99 stang
Coated MLS gaskets.

Randy
Click to expand...

Hey Randy, hadnt seen a post from you in a while. Great to see you didnt disappear. A lot of things I have modified on my car came from reading your posts. I am getting ready to dyno my car with the new M112 blower. I installed a 3.65 SC pulley running off the stock jack shaft pulley. Car pegged the stock gauge as soon as I stepped on it. I also have a 3.1 pulley for the car but I am afraid it will top 20lbs of boost when installed. I can swap out pulleys in about 5 mins if need be. Was thinking 18 to 20 max with all my mods and the menthol injection. Car has stock cam and heads.

Ken
 
I don't have stock internals in way of no mods, but stock in way of 115K miles. Only items changed in longblock were cam regrind, stiffer valve springs, longer pushrods, and porting to the heads/intake. But strength wise the only advantage I have over you is the valvetrain components...which probably have very little to do with boost that your cylinders will see.

Headgaskets are felpro paper gaskets with about 20k miles on em. I'm seeing 19.25 boost (logged on dyno) and use 93 octane with no alcohol injection. In the cold, with a carload of people, going uphill its spiked up to 20-21 psi. If I were you I would not go over 20psi (but if you happen to see a 22 or 24 psi spike during testing I don't think the engine will explode)
 
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Ken,

If your not sure of the amount of boost your making, I suggest pulling the octane plug/spout (to retard the timing 4 degrees) until you get it tuned.

David
 
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Micahdogg said:
I don't have stock internals in way of no mods, but stock in way of 115K miles. Only items changed in longblock were cam regrind, stiffer valve springs, longer pushrods, and porting to the heads/intake. But strength wise the only advantage I have over you is the valvetrain components...which probably have very little to do with boost that your cylinders will see.

Headgaskets are felpro paper gaskets with about 20k miles on em. I'm seeing 19.25 boost (logged on dyno) and use 93 octane with no alcohol injection. In the cold, with a carload of people, going uphill its spiked up to 20-21 psi. If I were you I would not go over 20psi (but if you happen to see a 22 or 24 psi spike during testing I don't think the engine will explode)
Click to expand...

That what I am looking for is people who are running a lot more boost than stock and if I will blow out the head gaskets runnin 18 to 20lbs of boost. I dont think I would feel comfortable running over 20 for an average, I will wait and see what I find out on the dyno

Ken
 
kenewagner said:
That what I am looking for is people who are running a lot more boost than stock and if I will blow out the head gaskets runnin 18 to 20lbs of boost. I dont think I would feel comfortable running over 20 for an average, I will wait and see what I find out on the dyno

Ken
Click to expand...

I see up to 22lbs of boost with all stock internals except for a mild cam and have not had any issues. I do have a FMIC but no snow kit.

I also agree with David's suggestion that it may be prudent to pull some timing initially. It certainly won't hurt anything.

Ira
 
I have been running 19-20 lbs. all last year and have had no problems. I did have a slight miss at higher RPM's so I swapped plugs to standard copper Autolite 103's gapped at .042 (I think thats the gap, they are a heat range colder than stock), and it went away. I have only put about 1200 miles this setup, but I did make 6 passes at the track in one night without blowing the headgaskets. I only have boltons with no internal work done at all.
 
Should I drive it again I will pull the octang plug to be safe. I was more concerned about blowing a head gasket at 20lbs of boost. It seems there are more guys out there running these levels of boost than I thought. I guess once on the dyno it will be just finding the right pulley to get the boost I want.

Ken
 
Detonation will blow your gasket quicker then the boost will. Pulling the spout is a great idea and dont see 17-20psi being a problem. I had run 21psi with my old ESM DIII and never exploded or blew a gasket..with the larger m112 exhaust and a front mount I'd think your be ok.

But yeah get it tuned
 
I also agree with David's suggestion that it may be prudent to pull some timing initially. It certainly won't hurt anything.
Click to expand...

Bahhh, the knock sensor will pull it for you :)

I think Julian may have seen 22 and 24 psi boost levels. As far as I know his bottom end is stock, but at that level you run risks of ripping the TB flange off the inlet :) (I think yours is beefy enough though)

Also, when I limped Ira's car around with Damon's blower (before they owned each of them)....you would not believe the boost I was getting. The car wasn't moving any faster from say 15-25-X? psi, but in that case as well...nothing exploded.

Micah

P.S. You should run a "Neibert style" boost gauge off the intake, up the wiper cowling, through the d-side window and laying in your door side compartment....as a quick, yet accurate way to tell your boost.
 
P.S. You should run a "Neibert style" boost gauge off the intake, up the wiper cowling, through the d-side window and laying in your door side compartment....as a quick, yet accurate way to tell your boost.
Click to expand...

It may look cheesy, but it works great for those rare times when I actually need to know how much boost I'm making. I especially like being able to hand it to someone else to watch, so I don't wreck the car while watching the stupid boost gauge.

David
 
David Neibert said:
It may look cheesy, but it works great for those rare times when I actually need to know how much boost I'm making. I especially like being able to hand it to someone else to watch, so I don't wreck the car while watching the stupid boost gauge.

David
Click to expand...

I have another line I installed running off the lower intake plenum into the interior. I have just a 30lb pressure gauge that I have hooked it up to but am not sure if it will work since it is not set up to register vacuum, just pressure. Cant drive the car right now as the weather sucks and I havent been able get down to my bay to work on it.

Ken
 
Ken,

I use an autometer 30 pound boost gauge that has about 8ft. of that hard nylon tubing attached. I just tee it in at the fuel pressure regulator (easy to reach on my car).

The rest of the time I just use the full sweep electric fuel pressure gauge and make the assumption that pressure is increasing 1:1 with manifold pressure. With 43.5 psi base pressure, I should be seeing about 63.5 psi at WOT.

David
 
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