Boost Level Saftey?

[kinger9]

This is the problem everyone gets caught up in. If you want to run pump gas or cheap out of fuel fine. The original poster wants to know how much boost he can run on a stock engine, and not cheap out on the fuel. Completely different.
We are talking making power not saving money.

The first post I made was reffering to the comment you made about it being counterproductive to lower compression to raise boost. Yes you lose about 4 hp but you gain 40 and I was trying to illustrate that I didn't agree with you.

2nd post I made I went through the spreadsheet and did all the math for racinstation since he couldn't take the time to do it himself and showed the octane requirements for each level of boost just like he asked.

I was trying to be helpful in #2 post and share my experiences with head shimming in the #1 post is all.

 

[RACINSTATION]

Kinger, no bashing on you man. I appreciate your input and it is not that I can't take the time to do the math myself. Believe me I have done the math. What I am looking for are real world case studies to base a theory on. If the math says that I can run 15psi boost at 6000 feet elevation with 91 octane fuel and I have 3 instances where detonation occurred in those conditions it is easier for me to find that out from someone who has "been there and done that". Also, conversely, if the math says I can only run 10 psi on 91 octane at 5000 feet and I know 10 guys running 15 on 91 at that elevation, then I could form my opinion based on that.

What JSCC is saying is that I was asking for info on stock compression, stock internals and people get carried away saying you can do this or do that and the thread takes a tangent.

 

[irondave86]

Are the octane numbers calculated above for a shimed motor or non shimed? MPI told me I could run my SC nytro at 17lbs on straight 110 with stock internals and stock injectors @ 3 - 5000ft. I thought it sounded a little off, but I tried it and to say the least it didn't work. So I bought new pullies now Im Around 12 - 14lbs but the clutch setup they gave me was way off so I'll see what boost I'm at once I figure that out. Like racinstation was saying I will spend the coin on good fuel, I just don't want to be pushing the motor too hard.

On a side note I do like MPI's product and customer service but there tech info seems to be in left field.

Thanks for any info, and thanks for the good thread.

 

[RACINSTATION]

I know the stock injectors max out at our elevation at around 15-16 psi. You can bump up fuel pressure to get a little higher but it is a band-aid.

 

[gunnerthesnowman]

i ran my apex with stock compression at 15-16lbs boost on vp c16 strait for a year... one day i turned it up to 18lbs boost and blew the head gasket right away... just a FYI

No dought, with out good timing control ,and block mods , good fuel will only do so much.

 

[irondave86]

I know the stock injectors max out at our elevation at around 15-16 psi. You can bump up fuel pressure to get a little higher but it is a band-aid.

What's your elevation? My afr's went off the gauge with my red and green blue all the way up, but i was seeing almost 18lbs of boost. I am using a 1:1 reg I didn't Really want to get a rising rate if I didn't absolutely have to. I'll probably try NM's kit when it's available but I also would like to know what this motor os capable of in stock trim, and what fuel I'll need.

 

[RACINSTATION]

7 to 10,000 feet elevation

 

[Habich76]

Why is no one mentioning H20/meth injection?
I have been running Stock compression & internals at 15-17 psi on 91 octane for a full season now with Hurricane's Meth system and no issues. The cost of the Meth system has already been offset by the race fuel that I haven't had to buy. The thing is a beast down low and tries to rip my arms out of my shoulders all the way to 8900RPM.

DIY rear mount, Garrett 2860RS, RB3, snow/air intercooler, Hurricane H20/Meth system with (3) 67ml nozzles & 50/50 water/denatured alcohol.
Bosch fuel system, 1:1 regulator.

Definitely worth considering.

 

[RACINSTATION]

Habich: We have had great luck with meth, and it is a viable alternative. What elevation are you running at? Is it the Nytro?

 

[Habich76]

Mostly 2-6000 feet Yes a 2008 Nytro MTX

 

[JSCC]

The first post I made was reffering to the comment you made about it being counterproductive to lower compression to raise boost. Yes you lose about 4 hp but you gain 40 and I was trying to illustrate that I didn't agree with you.

2nd post I made I went through the spreadsheet and did all the math for racinstation since he couldn't take the time to do it himself and showed the octane requirements for each level of boost just like he asked.

I was trying to be helpful in #2 post and share my experiences with head shimming in the #1 post is all.

I understand your point, and it is well taken. The only point I am trying to make is that to make power, you don't remove the items that make it. Compression is one of the easiest things to add to make more power, why take it away. Fuel not being an issue.
I don't think these engines have enough compression as it is so, it makes it even worse to remove more of it. In my opinion anyhow.

 

[JSCC]

No dought, with out good timing control ,and block mods , good fuel will only do so much.

Timing, especially with added compression is very, very important. But expand on the block mods a little. Has the block had issues holding together?

 

[gunnerthesnowman]

Timing, especially with added compression is very, very important. But expand on the block mods a little. Has the block had issues holding together?

Depends on how much HP you are making , the top of the cylinder bore is unsupported , very little surface area for the head gasket to seal to and under higher HP it moves an breaks the head gasket seal .

 

[Zipperno]

Depends on how much HP you are making , the top of the cylinder bore is unsupported , very little surface area for the head gasket to seal to and under higher HP it moves an breaks the head gasket seal .

This for a Nytro? The block has alot of surface area vs. 4 cyl. apex/rx1.

But it still is gasket failures with high boost. Why?

 

[JSCC]

Besides cylinder to cylinder wall thickness, there is a lot of head surface! I wonder if studs alone will cure most problems?

 

[Tarzannr1]

What about driving without headshim? boost 21 psi? Low boost piston
Stock headgasket is better than splitted headgasket and chim?

 

[BigFish BC]

Besides cylinder to cylinder wall thickness, there is a lot of head surface! I wonder if studs alone will cure most problems?

yes not allot of meat between the cylinders thats where most fail,oringing will help. so would retorking the head bolt after a few heat cycles after doing motor work wich is when most headgaskets go.

 

[Tarzannr1]

yes not allot of meat between the cylinders thats where most fail,oringing will help. so would retorking the head bolt after a few heat cycles after doing motor work wich is when most headgaskets go.

Yea i think to that retorking the head bolt is one of the ways to go to get it to hold.

 

[KFSNOW]

I ride a stage 1 S/C Apex spinning at 8-10 psi @ 8k to 12k elevation, I have about 5500 miles on sled, I've run only 91 octane non-ethanol fuel in it and have had no issues. I some times throw a gal of 112 race gas in but I don't make a habit of it.

 

[BigFish BC]

Yea i think to that retorking the head bolt is one of the ways to go to get it to hold.

unfortunately its a pain on these motors to do but its manditory on any car or diesel motor after doing head gaskets & studs sometimes they retork 2 or 3 times.