Stock block, crank, rods forged 8.8:1 pistons, AFR 185 heads HP Turbo Stage one kit. Just got the motor back together from previously bending some rods and was wondering what people are running on pump 93 with similar combos. Also have a LM1 wide band meter haven't installed it yet but will this help me determine the limits of pump gas. What I mean is when slowly increasing the boost the AFR will rise so once I am beyond timing and fuel adjustments does that let me know when I'm at the limit of fuel octane?

I think I am making this more complicated than it should be since I would like this motor to last longer than 800 miles..

 

I wouldn't go over 12 on 93. Anything above 12 your asking for it.

 

Thankyou very much. Just need to figure out this wideband and I should be set.

 

If you have a really good intercooler I might hazard a guess at 14psi, but since this isnt my engine I'll agree with 12. Water or alcohol injection can help. The wideband wont help with finding the 93 octane limit because the A/F ratio wont change. It will help you tune it, though. You'll probably find the limit of the block first, though.

 

On my all stock motor i started out with 9psi on pump with no problems (with IC ). during the winter months the car was pushing 13.5 to 14psi. i would have some detonation if the outside air was above like 75*. the increase in boost was due to a combination of cold air and boost creep. honestly i would have never increased the boost above 10psi ,but i didnt have a choice in the matter. before i could upgrade to a bigger wastegate to battle the boost creep ; i got owned by a tree.:tear:

 

I ran 15 non intercooled on an iron headed 9:1 motor. I think everyone is just WAY too conservative with boost levels on pump gas.

A friend of mine has been daily driving his S-trim car for a while, 16 pounds non intercooled, 93 octane, 9.5:1 compression. I talked to a guy on the corral, he's running 18 pounds of boost on 91 octane pump gas from an intercooled YS-trim into his 8.8:1 motor. Wolverine on here ran 15 pounds intercooled into his 9.5:1 motor before he would see some pinging on 93 octane, and he's in the florida heat.

 

Good info guys. I wasn't sure if the pump gas wideband question was retarted or not. So in reality the only way to know the limit is to here/listen for pinging or detination correct.
So turning the timing down would help also correct but to find the limit to when I would start losing HP I guess I would need to dyno or tune at the track?

 

You will be ok with 15psi depending what timming you are going to run.

 

I ran 15 psi on 92 octane with 8.5 to 1 compression. no problems ever.

 

I have a stock 9.0 comp motor with a H.P performance kit.

Buy having tfs twistedwedge aluminum heads and the timing locked at 18 deg I run 14lbs with pump fuel with no probs.

I have the inclusive system with 42s 255 intank 60mm turbo
small turbo cam the car put 518 hp 620 lb torque to the tires.

 

Be awesome if you guys could post the total timing you were seeing with said boost.

 

maybe so being i cant really afford to pay $ every time i break some thing from pushing it to the limit. i rather play conservative and have the motor last then flirt with the limits of the stock motor; just to say i'm running 15psi.

 

Steve, I think 14-15 lbs of boost with those pistons and your compression ratio would be safe. And aluminum heads give you about a half a point less compression over iron heads. I'd keep your timing locked at 20 degrees. And you're right, the air fuel meter won't tell you the limit of pump gas, you'll have to listen for detonation and check your spark plugs for specs of piston on them. Now what you can use the LM-1 for is to datalog and detonation will show up on the graph.

Briane

 

Well, for what its worth, I'm running 15psi on pump gas, 8.8:1 CR, with intercooler. 32 degree's total timing on boost (40 off boost).

I've tested it up to 18psi, but like to play it somewhat safe.

 

32 degrees....

 

I should probably quantify it....its a motorcycle. Stock total timing was 37 degree's...I figured 5 degree's off stock was a good compromise.

Need some timing if you want to run at 11K RPM's

 

I'm sure some of you guys run 15# etc, but how often do you change head gaskets?

 

only once, and it was due to detonation related to the fuel system.

 

The guys is asking how much boost he should run on pump gas in his Mustang and you're gonna chime in about what you run in your motorcycle? What kind of relevance does that have with this conversation? At least you came back and said it wasn't a Mustang, he might have thought it would be ok to run that much boost and timing in his car, until he blew the head gaskets, or worse.

Briane

 

PSI? how 'bout 40psi?

start low, tune, and raise it. there is no magic number.