i have a Lt1 355 with 9.2 to 1 compression .i have a procharger p1sc non intercooled , how much boost could i run ? i also have water /alcohol injection ,so how much more could i run with that on?

 

someone has to be running a similar set up?

 

well dont know about your set up but mine is in the sig, and i'm intercooled seeing somwhere around 17psi, is your 355 splayed?

 

I would have to say to quit being a puss and run 20#. That way I can watch the parts fly the first time we race. By the way, I'm still gonna spank ya!HAHA.

 

Yeah right all i need is 8 pounds to beat you *****.Besides that first time you launch your rear end is going to explode ....now thats funny

 

can anyone give the man some help?

 

Going by ATI's chart on their site, you could go up to about 16psi. Now if the bottom end holds up to it, that's a whole other question.

 

it should hold up i have forged crank,forged rods and forged pistons,with a stud girdle and main studs.by the way this is non intercooled but i do have water alcohol injection.

 

Should work fine with that blowers max output and alky injection. I ran alky injection w/ approx 14psi of non-intercooled on a 383 with approx 10:1 compression, and pump gas.

Only drawback to spinning a small blower close to it's max rpm is the heat it generates. Of course, the alky injection helps to overcome that, but it's only on when your under boost, and you can see some pretty high AITs when cruising and not under boost.

 

I've run 11psi with no intercooler, (pump gas) with roughly the same amount of "static" compression. I pulled the motor apart to make some changes and there are no signs of detonation.

Raymond

 

Good point!

 

I'm going to try and run close to 20psi with a FMIC, alky injection and stock heads on 9.2:1

 

I see a lot of blown (up) motors in your futures. The lack of knowledge revealed by the questions and answers makes me very nervous. To even attempt an answer, the following info. would be needed.

CR
cam specs
specific piston being used
any coatings used
intended use of vehicle wrt how long it will be under boost
fuel to be used

In any case, the original question is not clear from the git go. I am not trying to be an ***, but "how much boost can I run?" is not a complete question. Is he asking how much boost can I run once, or how much boost can I run and get OEM levels of reliability, or something else? I will tell you this: how the car is used is perhpas the most important variable. There are blower cars running for years without a problem, these are the ones that aren't driven hard, in general. Drag strip use is fairly easy. A max of ~10sec at WOT followed by a significant cool-down period. Much less heat and stress on the motor than the way some poeple will use them on the street.

Rich

 

you make a very good point ...sorry for being so brief ..Here are the specs i am running.
cam-hotcam "not by choice but i already had it"
pistions -speed pro forged blower pistons
compression- roughly 9.2 to 1
i am mainly going to drive it on the street and i do beat on it quite a bit but not for long periods of time.
i go drag racing probably 4-5 times a year.

what i am looking for is the most boost i can make and still be fairly reliable

if i left anything out please let me know

 

If you run 12psi and the tune is good, you can expect reasonable reliability with that combo on the best pump gas you can get, See if you can find out the motor octane of the fuel available in your area, look for the highest motor octane, not the R+M/2 posted on the pump. In general, Sunoco is the best in this regard. Tune the car with a wideband, aim for an ~12:1 AF ratio. Do not beat on the car when it is hot, do not use WOT atl low rpm. Use an aftermarket ignition box so that your rev limiter cuts spark, not fuel like the stock PCM does.

You can run more boost, but above 12psi with that cam and static CR you will be shortening the time under boost that the thing will hold together because it WILL be detonating. Your PCM will also be pulling a lot of timing, so it may not run any faster anyway. I'd recommend sticking with 12psi if you expect it to last. Of course, you could crank the boost up to 20psi and drive like a granny.

Rich