This thread is great

Any new updates? Also I saw that you replace the sureflo scavenge pump but what did you replace it with?

thanks

 

Still driving the car every day, it just turned 201,000 miles! ABout a month ago I put a EP posi in the transaxle, and at the end of the October I plan to take it back to the track and see what the LSD does for it. I may also turn up the boost if I can get enough fuel. I am currently assembling a mild built 3400 with Wiseco forged turbo pistons (9.0:1), ARP rod bolts, heavier valve springs, and a balanced rotating assembly. I'd like to get lower 12's or high 11's with it, the current best time was a 12.59 at 114.7MPH at 10psi which I ran March '05. Thats pretty long ago!

I don't think my old oil pump actually failed. I later discovered that if I park my car in a steep hill with the back end down, some oil apperently runs back into the turbo, cauisng it to smoke a little the next time you drive it. I now have nearly 16k miles on my replacement pump (which is the same SHURflo pump PN 8000-643-236) and it is working perfectly. Now I just don't park with the tail end down hill if I can help it (if I do, its really no big deal, but if I let it like that for 8+ hours it will probably smoke out the exhaust the next time I fire the engine).

 

89jyturbo you should make your own web site.....great work man!

 

He has one, lol.
KHTurboFab

Good to hear it's still going strong! I thought somewhere I had heard that the current 3400 let go of a rod.

 

Steve, the first 3400 I had in did indeed spit a rod. Actually, the lower part of the #6 piston came loose and dropped the rod off. The piston 'dome' was still in one piece at the top of the bore, with all the rings and lands intact. I don't know if it was caused by detonation or not, considering the way the piston failed. I guess detonation can ring the piston hard enough to break the skirt and lower part of the piston without damaging the top half??? Funny thing is that it let loose when I wasn't even beating on it. I swapped in another stock 3400 and have been driving and abusing it for the last year, but I've been trying to get my forge piston engine ready to go in just in case! The current engine had 103 miles on it when I installed it; I added another hard 10-11k.

 

I might do a twin turbo rear mount set up Ive got the twin turbos and everything i basically need coming next month just need to find a way to learn how to mount it up

 

hey all. I am new on this forum. I was looking for info on RMT and found wat i needed. Although my car is not related to this forum I can somewhat relate to you guys because of displacement V6 3.0 (97 maxima). I will be doing RMT starting next week. I am going to purchase piping to feed into engine during this week. I will be using the same pump as 89JYturbo
since there has been success with it. I will be using a Garrett M24 which has these specs:

GARRETT Turbocharger (N1 type)
0.60A/R Compressor Housing
62 Trim Compressor Wheel (35lbs/min)
0.64 A/R Turbine Housing
79 Trim Turbine Wheel
I dont kno if this is a proper size turbo for RMT but it was used in another maxima and showed full boost at 3500 in the usual front mount setup.


My main concern is, How do i determine the size of piping that will go to the engine intake? I have selected 2.25" diameter for clearance reasons but will that be too small of piping? also, my MAF has 3" inlets, will the sudden change of 2.25" piping to 3" piping be an issue with air flow?
I will post pics next post. since this one is too long already.


thnx.

 

In the sticky at the top of the forum, "Read Turbochargers by Hugh MacInnes and Maximum Boost by Corky Bell." Both explain how to size the piping. You take your air flow, and divide that by the area of the pipe to get air speed. There's a certain limit to stay below, to avoid flow losses - 300 ft/sec? 30 m/s? .3 Mach? Someone can correct me... Something with a 3.

 

Hmmm. I have both books, I ought to look into this. My car uses a 2" charge pipe and makes 328hp to the wheels. I bet my charge velocity is near Mach 1!

 

wont the charge pipe depend on the turbo outlet size? I called a local turbo shop and they told me they always use 2.25 with no problem. I didnt tell them it was for RMT but i asked "wouldnt it depend on the distance between turbo and engine?" and he said it dosnt really matter he would still use 2.25". so i guess ill go with that. 2" would be awsome (better clearance) though but I am worried that there will be too much velocity. I kno there is a limit to how much velocity u should have in the charge pipe, "you cant exceed 440feet/second".

Also i will be using piping from an exhaust shop so its slightly thicker than the usual intercooling pipe. so 2" OD will actually be like 1.8" OD. so ill just stick with 2.25. Here are some pics of how i will be mounting my turbo. I will be rotating the compressor housing to point foward.

 

I think the traditional answer from when some of us “old timers” started playing with this around here was .3mach, but I’ve noticed that in the last year or so a lot of people are suddenly using .5 mach…. Donno if something actually motivated that change or is it just a typo that is becoming popular on the ‘net or even a “well, we got away with…”

In theory there is a perfect size… the volute on the compressor is a diffuser with a crossection that exapands at a specific rate and _the best_ possible setup is to continue that in the ducting at a specific included angle (usually between 7 and 14*) for a set distance till it doesn’t matter anymore (usually it’s about 12-18”). Past that you just try not making major changes or bends and you’re good.

There is something here that I’ve never been entirely clear on (never bothered to look it up because there is enough empirical evidence what works and parts have specific sizes…), Andris, maybe you know? I would assume that these velocity calculations take into account density, in other words, you should be able to flow 2x the mass of air at a density ratio of 2:1 (that 2x the mass = the same volume), is that right? Or is it computed like actual air flow through a compressor, irrespective of pressure/density and just using the measured numbers at the compressor inlet?

 

So basically I should keep the same diameter of the outlet of the compressor? Im going to measure it today when i get my hands on it, but it looks like its exacly 2.25 so its perfect.

Also i think the velocity is measured by the actual air flow. I dont think density is taken into consideration. My question is, if the air was more dense wouldnt that slow down velocity?

 

Dense air would not slow down your velocity when you factor in the volume. Dense air will force more volume of air which in return could possibly be more benficial than velocity itself.

 

Well so far I ordered RFL BOV, Tial wastegate with 7.2psi spring, and the oil pump. I might use my nitrous main line as the oil feed line(i wont be using nitrous no more if this works), its a bit long though (16feet) but i dont see a problem with that, only when i initially start the car that it will take oil long time to reach the rear. Also I just briefly position a long pvc pipe along the bottom of my car to see how clearance would be and it looks like i might have problems using 2.25" (the pcv pipe is almost 2.5") so I might have to go with 2" piping, hopefully there wont be a problem when the 2" pipe has to be enlarged to 3" MAF.

My only issue so far is knowing what size pipe to go with, 89JYturbo used 2" piping, but my turbo is .60AR compressor and i dont kno if 2" will cause too much backpressure and choke. Below is a pic of my turbo, i pointed out the measurements of the compressor outlet, maybe these measurements can help me determine the proper size of pipe, wat do u guys think?

 

Generally, slightly larger than the outlet of the compressor, but like I said, you want to avoid sudden steps in size…

Based on your pics… I would probably recommend sticking with some 2.5” just for simplicity sake, but if _I_ was doing it with that compressor outlet, well I’d probably calculate things to see what an appropriate size range would be and then build something that fits inside that outlet but still clamps to the outside and flairs out to whatever size I calculated to get rid of that nasty step in it. If that’s the answer you’re interested in, then we’d need to know what engine you’re dealing with, powerband, details, turbo… since it’s obviously not an f-body.

And

Yea, but it’s not that simple. Density ratio is proportionate to the pressure ratio (pressure ratio – losses). Now the thing is that when we’re talking about “X psi boost” we’re talking about a static pressure. As velocity goes down the static pressure goes up. The thing is that it works both ways… as the air leaves the compressor most people have it outlet of the compressor usually entering a slightly larger pipe, slowing down…, and that happens every time you change cross section, at the TB, intake runners…

Every time that I’ve ever seen anyone attempt to calculate velocity they’ve always skipped any pressure/density calculations and just used the compressor inlet air flow to calculate velocity.

 

Good info, Well me and my buddy were thinking of using a dremel to smoothen out that step but we might risk going thru the wall. so we're just going to leave it as is. I see what ur saying of being able to fit something inside but still clamp to the outside. that might be hard to do. To give u an idea of my powerband heres a pic. Also i have a 3.0 v6 (VQ30), turbo specs are .60 AR compressor, 62trim compresor wheel, .69 AR turbine housing and i think 79 trim turbine wheel.

 

Ok, I just played with this and the numbers are coming out reasonable so I think my math is OK… I’m also assuming that velocity stays the same with boost, just density increases…

That being said, to make your current 193 hp at the wheels you’re making about 241hp at the crank, which will take about 320cfm worth of air (assuming NA and at 90% VE).

440ft/second is a little over mach .4… to keep that volume under that velocity you need an ID of 1.49”

.3 mach is about 326ft/s…. that works out to an ID of 1.73”.

Since the tubing that we’re talking about is measured in OD, is typically16 or 18 gauge, and even with mandrel bends there will be losses in the bends, I would say that 2” would be the absolute minimum before you’ll start seeing significant losses due to ducting, and if it was mine I’d shoot for 2.25” or more.

How’s that?

 

that sounds very reasonable. I guess im going to see how I can rout the 2.25 piping without having problems with clearance. Thanx alot.

 

The other thing to factor in is that most people always want more later on. When I size up turbo outlet inlet pipes I tend to go bigger than I need. I look at how much room I have and decide what pipe would fit nice then I buy the next size up. It takes less time to build it once with bigger pipe than doing it easy the first time and then the hard way the second time. 2.5" pipe is very close in price to 2.0" pipe.

If it was mine I would go with 2.5" OD pipe. Seeing that it can fit just about anywhere.
Even if you have to notch it here and there I think it is better off using that.

In terms of bends after the compressor outlet, the Holset clamp-on elbows have a 90* bend right at the outlet for the HX55 stuff and the HX35s have a 90* elbow cast right into the compressor housing.

 

83 Crossfire TA,
Take a look at the gnturbocalculator.xls spreadsheet. The pipe vel. calcs. at the bottom of the sheet take boost into account.

Using the calculator, for the commonly used 210 cfm before pressure loss it puts you at a 2.25" or bigger pipe depending on boost and air temp.


EDIT: Also, take into account the cfm loss due to all the mandrel bends to get to the intake.

 

Do you have a source for it? I have turbocalc.xls and it does have velocity calculations in the last section, but they appear to just call more boost=more dense (if you enter the same size tube before and after the compressor, the difference in velocity is proportionate to the difference in density resultant from the pressure increase)

 

It sounds like the same calculator I was talking about with the velocity calcs at the bottom. The header for the section is "Pipe Velocity Calculations" with two bold lines around it.

It uses the pressure density, CFM, and pipe area for the calculation. I think you are looking for something that takes velocity into account in terms of pressure loss. The way I see it is the outlet pipes, TB, etc. have an average area and between the comp. outlet and piston there is an average pressure drop remains constant/static. I don't know of any calcs that take into account the static pressure drop and velocity.

As with most things I don't completely understand and just have a "feel" for, I go over-kill with the stuff using the general theory. 2.5" out pipes for the T3s and 4" for the 7Xmm and bigger comp. outlets.

 

Naw… actually after working out the math (really pretty simple once you figure out that it’s easiest to do by converting the cubic measurement to ft x ft x in rather then ft^3 or in^3), I realized that what I was worried about really didn’t matter… I’ve got a good handle on it now as long as I remember to convert all the time units to either min or seconds and not mix the 2 and get weird numbers.

 

Well it seems like i got the piping coverd thnx to u guys.
Now i have a question. i got a oil pressure gauge. Where should i hook it up too? the T at the motors oil pressure switch location, or the return after the oil pump, or where?

 

'T' it at the oil feed. There is no need to know the oil pressure in the return line (there will probably be little or no pressure there anyway).

 

ok thanx. a question regarding the oil return. When the oil drains out of the turbo into the thick return hose that loops up into the trunk. is the pump strong enough to pull that oil thats sitting at the bottom of the hose while the car is off but the pump on. Because I wanna set it so that when i turn off the car the pump will remain on for certain time, i just dont know if the pump will be able to pull that oil from a lower level like that.

 

Yes, the pump is rated to pull oil 2 vertical feet.

 

From a fluid dynamics perspective, you can calculate the pressure drop or flow losses based on the piping size and geometry. If anyone is interested, I can dig out my old Fluid Mechanics notes.

MaxBoost uses .4 Mach (450 ft/sec) as their rule of thumb for upping tube size.

Another rule of thumb is each 90 degrees worth of smooth bend is good for a 1% flow loss.

One other thing to consider is boost lag. From Maximum Boost (p. 49),
Time = 2* Volume / Flow Rate

For a 2" pipe, 18' long, volume is 679 cubic inches. 2.25" has 26% more volume (859 cu inches).

For 150 cfm at cruise: 2 * 60 * 679in^3 / 1728 / 150 cfm = .15 sec
2.25" would be .2 seconds lag.

 

How do you determine the volume, I have calculated more or less my piping to be about 19feet long and 2.25" diameter with four 90degree turns. the rest of the piping is straight line. What do you estimate my time lag to be?

 

Using the info askulte posted:

19' of 2.25" pipe: .15sec * (19/18) * (1.26) = .2 sec
The (19/18) is for you using 19' of pipe
The 1.26 is for you using 2.25" pipe instead of 2.0" pipe

Including 4 90* bends: .2 * 1.04 = .207 sec

Using the 450ft/sec comes out to 745cfm MAX. for 2.25" pipe. Using the generic 2.2 HP/cfm then it comes out to 338 HP. That means these calcs also recommend 2.25" or 2.5" pipe.

 

I almost have everything needed for my project, i have BOV, Turbo, oil fittings for the turbo and the feed T on the stock pressure switch, oil feed line(im using my nitrous line for feed) 370cc injectors installed, 255 fuel pump on its way, z32 maf on its way, oil pump on its way as well along with the wastegate. All i need to do is just go to few blocks down my house and get about two or three 7' long 2.25 pipes and find me come couplers. and im set. ill keep the thread updated.

 

This is what it looks like:

http://www.chevyhiperformance.com/te.../photo_08.html

TV

 

Well, here is an update of my project. right now i just came from having my turbo and WG flange welded, it looks like it belongs in there lol. all i need now is a lil dump tube for the outlet of the turbo exhaust and run charge pipe and oil lines and im ready!!! here are some pics.

 

Andris, not picking on you or anything, but I’d suggest confirming anything that you take from ole corky there before using it… everything that I’ve bothered double checking (not what you quoted here), I’ve found to either be made up, rule of thumb that was not necessarily accurate or just wrong in some way. Suprising from an engineer….

Huh… I guess that the real question is how much of a loss do you have at both points(.3 and .4mach) and decide for yourself. I’m sure that there is a chart somewhere, can’t think of where to look… maybe I’ll as my wife (librarian at a university research library that deals with a lot of engineering problems…)

What radius? I’d bet that a 12” radius, 3” 90* bend has a lot less flow loss then a 3” radius, 3” bend… I hate rules of thumb. In this case I suppose that it could be useful if we knew that it was determined for the radii (probably as a percent or ratio of the diameter of the tube) used for exhaust bends…

Does this one bother anyone besides me (and if it doesn’t bother you and you’re following please explain)? Any little bit of flow above what would happen NA into the tube would increase pressure over the whole length almost instantly, so as soon as the compressor starts moving more air then the engine you should have a pressure change EVERYWHERE between the compressor and the engine proportionate to the difference in flow rates and the volume. To even make this a useful number we’d have to define how big a pressure change is something that you’ll feel and then lag would be how long it would take the compressor to increase the pressure in the plumbing between in and the engine by that pressure.

 

Anyone figure out what pump that is yet? I’ve got a couple of candidates that I need to c check out but haven’t yet. It’s surprisingly similar to the Holley and similar carburated fuel pumps.

I’d love to see a wiring diagram of what they’re doing there. I can’t figure out what that hobbs switch is doing there between the pump and turbo. I’m pretty sure that they’re not accurate below about 3psi, and any pressure in the oil return after the turbo would force the oil out the seals at the ends of the turbo shafts, so I’m not sure what it’s accomplishing.

I know that they supposedly use 2 pressure switches in their installs, one I believe is plumbed into the pressure side ducting, but I don’t believe that I’ve ever seen in any pictures, apparently they run the oil pump with a resistor inline under light load to run it slower, and then under heavy load (once that hobbs switch sees boost) it bypasses the resistor and the pump runs at full power. The second is supposed to turn on a light to tell you if you’re having a problem with the oil system. Not sure what they’ve defined as a problem with the oil system, and if that is what the hobbs switch is doing between the turbo and the oil pump I can’t imagine what it will really warn you about that you won’t see out your rear view mirror.

 

I have never bought or read the C. Bell's book and the more I read about says that it isn't worth buying. He always seemed like a marketing engineer more than a design engineer. The whole thing about flow here......it should be more about pressure drop. In the example above, it is about starting the engine (0 flow) and then going WOT instantly to max boost / max. airflow). The delta airflow needs to be used. But then interia needs to be accounted for.

In terms of the pic/link posted. It doesn't come up for me. If they have a sense resistor then they can sense for 0 current (full voltage at the motor side) and trip the LED/light as a warning that the motor stalled. They probably run the motor on voltage though the resistor for low speed and bypass the resistor with full voltage via a Hobbs switch when under boost. Here is a diagram.

 

Wow, after spending almost 2 days!! trying to figure out wat to do about the oil and how to rout it, i finally hooked up the oil. and also mounted the turbo onto the exhaust. no charge pipe yet. tomorrow or sat. but WOW!!!!! the sound is insane sounds like a freaking grand national lol. drove around for a while. no leaks everything is good. oil is spitting out of the cap on the valve cover so seems to be flowing fine, also no smoke or anything. so far exhaust and oil part seems to be done =).

BTW, i have a tial 38mm wastegate with a 7.25psi spring. do i need to provide vacuum even though i have a certain psi spring? (i am not using boost controler)

 

Cool. Sounds like your getting to the fun part. You'll be boosting before you know it!

For the WG, just hook the lower WG port to the compressor discharge ar charge pipe near the compressor outlet. Most turbos have a 1/8NPT fitting on the discharge for you to connect the WG sense line. No sense in running the boost sense line all the wa to the front of the car.

 

Streetzlegend… be careful… without any charge piping the turbo isn’t working against anything and there is nothing to keep it from overspinning and flying apart on you.

The 7.5psi spring is an average of that pressure (it will probably start opening at around 5psi, and be fully open at about 9) with the signal line connected, it will not just force the valve open via pressure on the valve at 7.5psi.

Heh, the whole second part of the book is an advertisement for his aerocharger, what’s uneque about it, installs using it…, most of the first section of the book is “rules of thumb” and little _actual_ data, which seems slanted towards smaller turbos like his aerocharger… you be the judge.

I need more sleep or something, I’m not following how you’re sensing that the motor is stalled…

 

thanx for advice. Well tomorow im doing charge pipe, the oil system has been a nightmare lol. i got it hooked up fine now. i had several leaks, also this morning i had a puddle of oil below the turbo. and im almost sure it was the feed line draining oil back into the turbo overnight through the seals. i am using a long nitrous SS line so the extra line i had it in the trunk coiled up, so i imagine since it was in the trunk all that oil up there just went down. Now, i changed that feed and located the extra line in a coil almost same level as the turbo. i also leave the oil pump running for long time after i turn off the car, and i still get a puff of smoke when i turn it on, i dont kno why. im thinking maybe the feed is still moving air into the turbo.. don kno wat to do to resolve that.

EDIT: also, forgot to mention or ask, is the shurflo pump supposed to be mounted in a certain position?

 

I came across that aerocharger when searching for motorcyle turbos. In theory, the design was great with no oil lines. In reality, it needs oil and cooling. Overall, a POS. They went out of production.


It gets a little more complicated. I was leaving out the details because I didn't think anyone would care. The warning_light/ckt thing is a circuit. The ShurFlo will draw a max. of X amps. Lets pick 10 amps for this example. Using a 0.1 ohm sense resistor means the voltage drop would be 10 * 0.1 = 1 volt. This is a feed to a voltage divider and then to a Microprocessor A/D input (or about 4-6 NPN/PNP transitors for voltage comparison). The Microprocessor turns on the LED if the voltage is too low or two high (or the NPN/PNP turn on the LED).
If I was to use the ckt, I would feed the sense voltage to the stock 730 ECM fuel pump ckt with the voltage divider already in the ECM. It is designed for sensing voltages up to 25 volts. A code change would be necessary. The stock fuel pump voltage sense is kind of pointless is some aspects. Another cheap way is to use an Atmel AVR (about $2).


I never tried a RMT setup. If I did, I would make small tank for the turbo return side with a fitting on it to the oil pump. Small as in only large enough to hold the amount of oil sitting in the feed line. Using 16 ga. or heavier steel. It would probably only take a few hours to build and would save the oil seals. The tank would bolt to the turbo oil return flange. I wouldn't be surprised if that is what 89JYTurbo ended up with.

I always thought the oil seals where designed to keep exhaust out of the oil and the exhaust pressure kept oil out of the exhaust.

 

After spending the entire day doing piping. I am officially turbo charged!!!

i had serious problems when i first started the car because i routed the vacum hoses for the pcv system wrong. so ALOT of oil went into the engine, so much that out of my exhaust flange on the y pipe was leaking pure oil. after like 20mins car running, all the smoked cleared up (after fixing pcv system). I also had alot of problem with my MAF the car kept bogging and just not running properly, it may have been from the oil hitting the sensor so I put in my factory MAF and car drove fine, then started poping a hose but we didnt kno it was a poping hose, we thought it was the MAF so we started disconnecting the vafc2 and just troubleshooting everything electronic. tomorrow im putting the electronics back, put a barb on the charge pipe for the wastegates signal hose, change plugs, and go for a drive. after fixing things today, i drove around and showed 5psi at 3,000 rpm in part throttle. didnt go WOT because the WG will not open and ill be at full boost and pop the motor.

The other problem i still have is the oil seeping into the turbo after parking for a long time. Very soon I am going to install a spring loaded check valve on the feed of the turbo (since thats the one that causes leak into turbo).

ill have some pics soon, thank you all for helping me i really appreciate it. ill keep this thread updated on this.

 

Sounds good. You can buy MAF sensor cleaner at the auto parts store to clean off that oil mess (its made by CRC). I do that often on cars with oiled filters like K&Ns when the customer puts too much oil on. Makes the sensor read like new.

The oil draining into the turbo- do you run the oil pump for 30-40 seconds after the engine is shut down? If not, there is a lot of oil in the drain line yet and that will leak back into the turbo, assuming the pump is mounted above the turbo as I have in my Z24.

-Kenton

 

yea i have my oil setup exactly like yours. and yea i leave the oil pump on almost a minute after car turns off. thing is, i hear the oil being moved to the front no matter how long i wait. i guess there is ALOT of oil in there. im thinking, maybe i used a return line that was too think, i think its a -8 line.

 

Well I have been driving around alot for a few weeks and no problems yet. just some oil on the charge pipe but i am almost sure thats because of the feed. i gotta do something about that. Other than that, this project is 99% succesful. Thank you all for ur help. Now I am going to work on water/alky/meth injection, don kno which one yet. As for the cars performance, I ran a 350Z and he stayed bout 1 car behind me for the whole run, we went up to 90mph or so, also ran a stock srt4 and we were dead even side by side from 30mph -100mph, I also came across an R32 GT-R skyline stock. I see him take off from behind me on the other lane and i take off as well, he got to my door and never passed me. it was stock so its not that fast. basically according to how the car performances I should be in the low 14's. I should be visiting the track soon.

 

wow my car ran low 14's out the dorr. What kinda motor set you have?

 

Its a 97 Maxima, 3.0 V6 DOHC, 190hp and 205tq at the crank from factory. its a high 15sec car stock. weight is about 3200lbs (my automatic model), FWD.

 

So is that just an adjustable fuel pressure regulator you are running??? I am looking to do this with my 92 cav. 2.2 but my turbo will sit in the negine comp.

 

update on my setup:

Well its been 2 months since i did my rear mount. everything is running PERFECT! i went to the track and ran:

1/4: 14.1@102mph
60': 2.3 (really sucks)

At 5psi untuned I dynoed 230whp. but I really dont trust that number because the dyno shop didnt even get my RPM signal (too much noise), so they based the dyno HP on the drum spinning instead of my rpms. so i dont trust it. I didnt get torque but it should be around 235lb tq. I am now at 7.5psi Tuned, not dyno yet, but the track times was with the 7.5tuned.

 

Im running a 2004 cavalier that's stock in the 15's at sea level and 16.6 up at the altitude here in wyoming. Im dead even with the civic si 2003 hatchbacks up until 70 when they take me barely. I have a t04 t3/t4 hybrid sitting here waiting to be put on. the muffler is so fricken huge i'm sure the turbo would sit better there instead. yes i realize its overkill, but as long as it will work, i'm putting it on. I have enough room to place it behind the motor in between the firewall but i dont want to. I like this idea because its easier to get to. The main question I have has to deal with the ecu; Will I have to remap the brain or will it auto adjust to the greater o2 levels? I have 57,000 on the car. I know the ecotec 2.2 has a higher compression than the 92's and other cars on this forum. its sitting at 10.3:1 and I know i can handle 8psi safely, but i will get the copper o ring grooved head gasket to lower it to 8.5:1 if i need to to get (input # here for me)psi. do i have to retard the timing in the higher rpms also like with NO2? help me get started i want to have this thing on by early summer.