boosted guys? plugs and pump gas at 8 PSI

Finally got my 340 running half decent on all motor with the FITECH 1200 after battling a whole bunch of issues with E85. Now that i'm on pump gas, after a lot of logging and tuning, the system finally seems to be adjusting correctly.

I am ready to throw the boost back at it, but since this will be the first time boosting it on pump gas I am very worried about what I should be doing.

It's a 9.2:1 c/r 340 with ported w2 econo heads (about 295cfm), a 242/246 112LSA .609 lift cam and forged pistons. Boost supplied via intercooled procharger.

Right now I have autolite 65's in it. The pulley I have on the procharger was making 8psi when I was on E85.

Should I be worried about 8 PSI on this engine using 93 octane pump gas?
I have FItech controlling the timing.

My biggest questions are, will this be safe? What plugs should I use (2 steps colder, 1 step colder)? What should I do about timing? Where should my AFR's be to start?

I was figuring I'd back my total from 34 to 32 and then retard maybe 1.5 degrees for every pound (so total at max boost would be 20).

I'm new to boost tuning and felt much safer learning on E85, but I figure if I start very safe and sneak up on the tune little by little (maybe with the help of a pro tuner on a dyno) then I will be alright. If there is any serious risk of trying to do 8 psi on pump gas with this then I might have to invest in a meth injection kit.

Atleast 2 probably 3 colder on the plugs and watch the plug gaps .026-.028 is where id start at.
Just take things slow and make sure everything is happy.

I think it will take a bit more WOT spark than that, like 25.
That may be too much cam, or at least too much OL.
Needless to say: start rich. Stoichiometric, 14.7, 13.5 etc. are not relevant, you have to run as dark as you need to, I would begin at 12:1 or richer. In general, the same degree of anti-knock can be achieved by mix or spark, but retard kills more power.
160 thermo.

How efficient is your intercooler?What heat plugs do you have now?

I would start out doing the ignition as you described, do not go beyond 12:1a/f. Rich mixtures are hell on rings, ringlands, and make it difficult to read plugs. Start leaning out the engine to the mid to high 12s. When it feels sharp/ clean, start reading plugs for timing. Add 1 degree at a time. Use ngk plugs, watch the straps. Try to get your burn line ABOVE the bend on the strap if on pure pump, or on the bend with E10 blend.
Spend a bunch of money on several sets of plugs. Be diligent about plug reading. Much easier and cheaper to screw in plugs than change pistons.

On your deal your way safer running 3 to 6 lbs. at max RPM to start with on tuning it on pump fuel
I would screw in a set of Auolite 3932 or AR63, if you want the to run the extended gap plug with the blower I was taught to run a retracted gap plug on any motor under boost
Good luck, don't get greedy on the power

I have taken sooty plugs,made a pass and they cleaned right up and gave a new reading after the change!

I personally like the NGK stuff better, I think it's a little bit easier to read the timing mark. I'd use a -8 plug at that boost level.

Interooled 8psi, just start it fat around 12:1 A/F and your 20 degree mark will be plenty safe. You'll just have to sneak up on it from there, just carefully watching the plugs for detonation.

Good safe starting point though.

Trendz is spot on... buy a lot of plugs, take the time to make a pass and remove all 8 for inspection. Change the plugs, bump the timing, and try again. You can buy NGK race plugs REALLY cheap on www.rockauto.com (like $1.20 a piece)

NGk 4554
https://www.rockauto.com/en/parts/ngk,4554,spark+plug,7212


$1.34 each

Thanks for all the replies everyone! I'll try to answer some of the questions:

Intercooler probably isn't very efficient. It's a cheap eBay special, but it is large (31x3x12 IIRC) and is right up front behind the grille so it's getting plenty of fresh air.
Specs from the intercooler from CX racing (if they are accurate)

----Compress Air Flow Rate: <700Cubic Feet/Min, Rated to 600-800 Max HP
Working Pressure: 5~50PSI
Pressure Drop:2~5psi@35psi; 0.2~0.5psi@15psi-----


Plugs in it now are autolite 65's and heat marks seems to be pretty much center of the bend with 34 degrees, but they are difficult to read. It was much easier to read NGK's from my past experiences.

Cam was spec'd by comp for my boosted application. I thought it was really big myself, but they had all the specs of the motor, head flow chart, what I planned on doing so I put my trust in them. Originally I was going to run this setup at 15psi on E85 and try to make some big power, but the FITECH never worked correctly on E85 . I'll probably try again at some point.

Problem with reading plugs for fuel is the nearest track here is 3 hours away, and not a lot of safe back roads where I can get on it and shut it down right away. I was considering just bringing it to a dyno tuner to make tuning easier/safer but I was still having problems with the blower belt shredding when I last left off on E85. I would love to get it running decent myself so I can address any belt shredding issues before spending money on dyno time, I could worry about making power later.



So from what I am hearing from you guys, for a safe starting point I'll do the following.

160 T stat

NG4554's

Start with total timing at boost at 20 degrees and a 12.1 AFR

I am thinking I may have to address cooling system issues, as I was creeping up to 200 in traffic before WITHOUT boost (cheap radiator, cheap proform low profile electric fans). going to see if I can fit one of my high flow derale fans in place of one of the pro flow ones and hopefully that will keep her cool. I think a lot of it is from the intercooler blocking the radiator.


To be extra safe, I think I have two options. I was going to pick up a 5.0" pulley that would probably drop boost down to 4-6psi. Because I'd eventually like to make more power than that though, I figured for the $120 I'd spend on the pulley I can put that towards a $280 meth injection kit. This way I can be safe and fast. Do you guys think meth injection would be worth it? Possibly make it more complicated to read plugs/tune it (IDK, never used meth injection before).

When you start tunning you may have problems with crank case pressure from ring blowby even if you have a good evac system

I have dual valve cover breathers to a catch can, total seal gapless rings on the forged pistons. The limited time I was on E85 with 8 PSI I didn't notice any signs of blowby on plugs/no oil in catch can or residue around breathers. All I noticed was puffs of white smoke from the breather which I thought was a blown head gasket (and prompted me to do a compression test) but went away completely when switching to pump gas. Not sure if that was normal with E85 or maybe the gas stations here just had crappy moisture ridden E85 in their tanks.

I'd start out on C-16 or Q-16. Get a handle on it and then move to pump gas.

Sounds like it's capable of making some power

He only needs to run 100 oct to run full timing!A waste of $$ with C or Q at 8.50 a gal.

The cam events for different forms of boost (turbo, centrifugal, Roots/twin screw) will be different.
Just for fun: ask Comp the same question for the same boost derived from all 3 sources...?

Dizuster has a pretty good advise, I run NGK 9's in mine but I have a different set up, i run pump gas 93 in mine on the street but at the track I run C-16 waste of money maybe but to me it's good insurance I do turn it up a little from 8lbs up to 11.5lbs by my Fitech data logs. Just start out conservative on your timing and boost level till it's safe. The Fitech is pretty good about learning fuel tables as you go I really like mine.

My point is more that he should use a fuel close to his projected compression ratio after boost

You seem to always have trouble with your blower combo. 💩

Thank you for noticing.

The static compression ratio does not change with boost.
The dynamic compression ratio does not change with boost.
The charge mass increases with boost.
The calculations such as new CR = old CR × (boost + 14.7) ÷ 14.7 are completely wrong.

Always assumed that was true, I mean by most of those calculators I have used, 8 PSI on a 9:1 motor comes out to something like 14.9 compression ratio. I know this motor can run on pump gas, although my worries come from my confidence in tuning and having a controlled environment to really check the tune, but if it were actually a 14.9 c/r with boost I don't think there would be any chance of it running on 93. You must be right about the cam too, I am assuming because the procharger builds boost with RPM unlike some positive displacement blowers, and works independent of the motor unlike a turbo, the cam seems fairly close to what I'd expect them to spec for an N/A motor. Not the first procharged motor of mine that happened with. On my chevy, I had comp spec me a cam for my procharged 396 stroker LT1 and the blower cam they spec'd was literally 1 degree off from the cam Brian Tooley Racing spec'd me out for when it was N/A.

I talked to a few local tuners around here and they all think I should just let it ride with the 4.75" pulley at 8PSI and 93. Everyone I've spoken to seems to think it would be plenty safe if I just start rich and creep up on timing/fuel slowly. I'm still a little worried though, I guess I just don't trust the accuracy of the FITECH (although most have had great success with it using boost) and I'm worried about starting too rich and hurting the rings.

Going with Meth injection is still on my mind.


I'd love to mix high octane fuel while learning the tune but from what I have heard, it'll pretty much be starting from scratch again dialing the tune in when I decide to switch to all pump gas...and I really don't want to be having to fill up with $10 a gallon race fuel all the time.

FWIW I did a compression test (cold, I know not ideal) the other day just to make sure everything was still OK with the motor since through most of its break in when I was trying to run E85 the FITECH was WAY overfueling.

All cylinders were within 4 or so PSI +/- of 175 and dozens of WOT runs N/A figuring out how the FITECH worked on pump gas with no sign of oil in the catch can, no oil film anywhere around vent hoses, no sign of blow by.

Not sure if the cranking compression tells you anything about its ability to run on pump gas; if it does, I am unaware of what that would be, but figured I'd share.

Have a nice day

Have a nice day

polyspheric, that is is some interesting stuff. It's crazy how unpredictable the power output would be just from adding boost. I guess when you think about it, it makes sense. Differences that may make a slight change in airflow on a motor at atmospheric pressure would be amplified when flowing 2,3,4 times+ the airflow through the same head.

What's the 2JZ in? Sounds like a beast!



So I broke down and ordered a stage 1 snow performance meth injection kit and 3 gallons of their "boost juice"I figured the motor wasn't worth $270 and if I want to hit the 550hp make I'll probably need at least the 8lbs.

I ordered Ngk br8es plugs

What do you guys think I should start with timing and fuel wise with the meth? Never tried this before, and I have some research to do on it this week but figured maybe someone here can suggest a starting point.

I know I may not have needed it, but it would make me feel more comfortable not having to monitor IAT's and give me a little more of a safety margin.

Have a nice day

1mean340, any pics of your car? Would love to see it.

Doesn't the effective CR chart apply!!
http://theblowershop.com/wp-content/uploads/2015/08/Effective_Compression.pdf
I pushed my luck on pump gas and ran out of octane...........

Call NGK they were super helpful and I was running too cold (9) of a plug and explained why to me. Also you want to run a resistor type plug with fuel injection. He also told me a projected tip plug weather copper or irdium would work way better boosted and fuel injected then the ngk non-resitor plug I had in it.

Im 8:1 iron heads, intercooled and run 93 pump up to 15psi
I run my timing thru a msd 6al2 programable and build my own curves. I dont start pulling timing until 5psi and pull 1 degree until 10psi and then 1.75 until 15psi

I called NGK originally when I was on E85 and the plug recommendation they gave me seemed way off from what I was hearing other experienced guys tell me. Not sure why that was, but I changed plugs based on the recommendation of someone on the FITECH boards who had a lot of experience with E85/boosted SBM's and it worked much better. I need a resister plug for the EFI, also I have always heard a recessed tip is what you want for boost so you don't get spark blowout? Not sure if the BR8ES's are too cold, but hopefully it's a good starting point.

IMG_2604 by Kris A

IMG_1393 by Kris A, on Flickr
for the gentleman who requested the setup pic, this is prior to cutting out a new main bracket out of .75" aluminum.

So much mixed info about meth injection out there. I have heard some say don't rely on it as a fuel source, it only helps reduce IATs. Heard others say that the reduction in IAT's is a myth perpetuated by saturated IAT bulb style IAT sensors giving false readings. Most people seem to be saying to tune it without meth then add the meth. Only issue is, I bought the meth kit so I didn't melt my motor down while tuning.

Have heard some say it will barely affect AFR's, other say it can drop them significantly and leave the fuel injection system to max out trims trying to adjust.

I had always thought rich would be safe, but others saying i'm looking for ring trouble if I start with a rich AFR.

Just want a safe starting point, mainly because I still have some belt issues with the blower and I would love to be able to sort them out before paying for dyno pulls with a professional tuner. I just need to be able to do a hand full of runs to make sure everything is working correctly so I'm not paying for dyno time to shred belts.

Right now I am thinking i'll set a target AFR of 11.7 and spray the meth (boost juice, basically a 50/50 meth water blend) as soon as boost kicks in. start timing at 22 degrees to be safe






More photos of the build here
https://www.flickr.com/photos/145918422@N04/with/33639843983/

I built the blower bracket around an SD concept crank pulley, built an alternator bracket to mount a GM 140 amp on the driver's side. Had problems with the blower throwing belts. Built a brace to the rear of the blower bracket and recut it out of 3/4 T6061. Seemed to help, but belts would still jump ribs and split in half every few runs. Alignment looks dead on. Thinking at this point it's either that Dayno tensioner isn't up to task and is bouncing too much or I am getting deflection on the idler pulley which is basically just a really long bolt and spacer (I have a fix I am going to weld up today) or the belt throwing may have been from the fitech bogging and hesitating bad with E85 as the sudden change in rpm tends to throw belts. But all that is whole other topic lol.

When they suggest something besides 50/50 water/methanol, it's frequently 1% acetone to help them stay mixed.