Tuning help, supercharged 96 4.0, sct tuners needed

[94Eddie]

The amount boost can play a huge part in detonation. The greater the psi, the hotter the discharge air from the blower. The hotter the intake air the greater the chance of detonation with a given tuneand the less power will be made . This is why intercoolers are so popular. They remove heat and allow more power to be made more reliably. Basically, the cooler the air, the denser the air and the more fuel that can be sprayed into the cylinders resulting in more HP along with allowing a more aggressive tune. Usually 6 psi doesn't heat the discharge air too much and a fairly aggressive tune can still be run.

Water injection is a very effective way to cool the discharge air from a blower. I used it to control detonation on a 16 psi a Kenne Bell 5.0L setup . I got to the problem of blowing head gaskets from the heads lifting on the stock block but detonation wasn't a problem. If you want to up the boost, or add another safety factor, it might be something to consider. The trick is to not spray too much water. It doesn't take much to cool things down. Also, a side benefit is the water keeps the valves and combustion chambers squeaky clean by removing carbon deposits.

 

[fishy2k8]

saying that 6psi doesn't heat the discharge air too much is a way general statement... intake temps are going to directly depend on the type of compressor being used to make that 6psi. using an unintercooled m90 for example is going to have way hotter intake temps compared to using a centrifugal blower.

high boost on the same compressor will raise temps. but temps can be way different at the same boost across the board of different types of compressors.

but again.. i'm not sure who you are trying to school on this subject. this was a thread about a specific tuning issue, not how to tune a forced induction vehicle, or what type of fuel to run.

 

[Jakee]

Yes, boost does have something to do with it. That along with the compression ratio equates to what's called "effective compression ratio" and the higher that goes, the less room for error in the air/fuel and timing. Dial all that in and then have your IAT's increase for some reason or other... and you find yourself walking down the street kicking a rock. LOL

 

[fishy2k8]

Yes, boost does have something to do with it. That along with the compression ratio equates to what's called "effective compression ratio" and the higher that goes, the less room for error in the air/fuel and timing. Dial all that in and then have your IAT's increase for some reason or other... and you find yourself walking down the street kicking a rock. LOL

and..? okay i never claimed not to know any of this..

 

[Jakee]

and..? okay i never claimed not to know any of this..

I typed that because I saw where you had stated "Boost has nothing to do with it". I know you probably didn't mean that but wanted to keep correct information flowing in your thread. Boost does have something to do with it.

 

[Jakee]

Changing the subject, did you know you could use a SOHC oil pan on your engine?

 

[fishy2k8]

no, my point was that 94eddie said 6psi is probably not enough to cause detonation with 10:1.. and i said boost has nothing to do with causing detonation.. it's the timing advance. yes, boost raises the compression and plays a part in easily detonating with a bad tune.. however, you lean a n/a motor out enough it's going to detonate too.. that's what i meant by boost doesn't have anything to do with it.

 

[fishy2k8]

Changing the subject, did you know you could use a SOHC oil pan on your engine?

yes sir! it's already got one on it

i put one on back in may due to my ohv pan cracking after replacing my timing cover gasket

 

[Jakee]

Cool deal!

I put the newer style mp90 on a friends mustang and I loved the way it sounded. The supercharger whine has always got my blood going.

And we found out real quick that even this newer version needed to be inter-cooled here in Texas. His cruising IAT's were around 160 (out of boost). Well maybe not actually needed; the tune was pretty refined with the fact it pulled timing starting @ 130 IAT's (so it was safe). But to get the most out of it we added the water inter-cooler in the X-charger manifold and then was able to add the smaller pulley to get his boost up. It made a world of difference. This was all done on the 4.0 SOHC

 

[fishy2k8]

nice, yeah my intake temps on the paxton are about 130 ish, but i've got an oil cooler to put on it that will help keep those down. I've been staring at the engine bay a bit because i want to mount a front mount on it to really cool it down it's just pretty tight in there with that blower!

 

[94Eddie]

no, my point was that 94eddie said 6psi is probably not enough to cause detonation with 10:1.. and i said boost has nothing to do with causing detonation.. it's the timing advance. yes, boost raises the compression and plays a part in easily detonating with a bad tune.. however, you lean a n/a motor out enough it's going to detonate too.. that's what i meant by boost doesn't have anything to do with it.

Timing, boost level, compression ration etc. all play a part in detonation. You can't ignore any one component when tuning. The 10:1 CR will narrow the window of what timing settings you can use. If it were my engine I would be considering water injection to add a safety factor. It is cheap insurance, IMO.

Centrifugal blowers have an inherent disadvantage when detonation occurs because it occurs at high RPM (5,000+) which is when the engine is under the most stress and detonation is much harder to hear. I like the Roots and twin screw blowers because detonation is usually detected at lower RPM levels when it is less likely to cause engine damage and it is easier to hear.

 

[Jakee]

I always thought the peak torque rpm range was the killer. That usually occurs much sooner than red-line.

 

[94Eddie]

I always thought the peak torque rpm range was the killer. That usually occurs much sooner than red-line.

It usually is for other drive train components like the transmission, differential etc. For the engine it is typically red line because at that point the engine is loosing its balance and the vibration adds to the stress level along with the stress from the horsepower being made.