Does any one know what the maximum capability of the m-62 supercharger is? What can i push the boost to without the supercharger comming apart? I was hoping for about 18-19 lbs. Is that feasable or will the supercharger come apart?

 

It has a maximum spinrate of 14000 rpm. 18-19 lbs would not kill it. Getting dangerously close though. Be sure to swap out injectors and plugs. I would recommend waiting for the stg kits to get that much boost however. This way you know it would be safe. If you put a stg2 on with a 2.8 pulley you should see 18 lbs.

 

I have just recently got this car and dont really know where to start exaclty. I just know that i want 300 hp. I have figure i could acheive this with full exhaust, CAI, ecu mapping, injectors and a 2.6 pully. plus the wide band O2 and of course fuel management system. I'm not exactly sure though. is that too much? what exactly are these stages that i have read about? I haven't heard exactly what they are except that there coming? when?

 

boost does not matter with a supercharger...given 2 identical engines with the same pulleys the one with less "boost" will be making more power. Boost in a s/c application is a measure of backpressure in the intake manifold. The more "boost" the more back pressure..that is bad. When the "boost" is low it means it is flowing better...which is good. The things you have to look at on a s/c is the blower efficiency charts and the max rpm. Also the higher the boost the more hp the s/c is going to take to turn and at a point will actually lose power not to mention the loss due to dramatically increased intake temperatures.

Dan

 

Well I know that about two weeks ago I drove next to a GM engineer w/ stg2 cobalt SS and he said that that run he was on was finalizing their testing. I also know when we raced he put 2 cars on me like a modded srt-4. 2.6 is too small you would have to grind the snout of the supercharged down just to get it too fit. Also you would be around 20 - 22 lbs of boost. Way too much on the m62 IMO.
Stg2 is supposed to put you at 241 hp well I am modded and probably around that area something like 235-240 and it walked me. Sooooo..... Also for the CAI you can make one out of your stock system. It will give you the same gains and you will save $260

 

I agree with Dan after a certain point you will actually lose power. I suggest to go no smaller than a 2.8 pulley.

 

Alright. In your opinions what do you think that I will have to do to get the 300 hp? Will the engine handle that ok? i heard that it will handle around 350 hp? is that true? Or will i get to the point that the head cannot flow that much? what exactly is the stage 2? What is in it? and Dan do you know what the best set up for the m-62 is? what is the most that you can spin it and still be efficient and not create to much heat?

 

Stage 2 will be, pcm reflash, injectors, 3" pulley, and smaller belt.

Rated to produce an extra 36hp and 18tq over the stock rated 205.

Considering most SS's dyno over 210, you should see close to 250whp with a stage 2 alone.

 

How do you maximize the m-62 on the cobalt? What is the point that the supercharger is just creating heat and loosing the hp? Is there anyone out there that is making a program for the cobalt?
That will let the supercharger boost past 16? I have heard from the guys at billetflow that the computer will open the supercharger up at 16 lbs. so that it cannot boost past that even if you have the pulley to do it.

 

I believe the blower limit is a continuous 14,000rpm. Thats full load 14,00rpm all day all the time. Over it every once in a while isnt going to hurt it. a 2.7 with stage 2 (6500 rpm ) will put it over 14,000 by like 1000rpm I think and a 2.8 will put it over by 458 rpm at 6500rpm engine speed iirc.

GM recommends replacing the pistons at over 300hp but twincharged is running just fine with an estimates 350+...With bolts ons I highly doubt we are going to need to change internals.

The way to make the most power is to make the engine flow air better because a internal combustion engine is a glorified air pump. Headers,full exhaust, ported head,intake manifold, tb, intake system, ported blower, cams will all increase power. I imagine we will see 270whp with stage2, intake system, and a 2.8 pulley. A block to tip exhaust added to that with a tb and maybe cams should get you over 300 whp on most dynos. That is my guess lowballing the hp claims

 

If you install a pulley hub, you can swap them out pretty quickly if you decide to use a small pulley at the track. Using a 2.7" at the track for a short amount of time will probably not hurt it.

 

I would not feel safe with probably not

 

Thanks for the info it is of cignificant value.

 

No problem...have fun with it kid...

 

BOTTOM LINE,
Keep it stock keeps it safe!

Other wise it is ALL a guessing game on how long part "a" last for driver "b".

The statement on boost was WAY off!!!

Example, at 1 time the L67 V6 w/M90 was said to be maxed w/3.0 pulley! Guess what, we are running 2.5's now and breaking records! I ran a 3.0, 2.8, and 2.6 on my Impala. The car gained 2mph and 2 tenths for each drop! Although it became progressively harder to launch. Boost went from 13, 16, 18.5 for each pulley. The key is keeping the air charge cool. I use water injection, some use methanol, others just run race gas.

Right now with the 2.7" on the cobalt, i'm seeing 16-17psi at 6500rpm. As for the limit, time will tell but there will ALWAYS be someone who gets more than average out of his/her combo

 

Rob is 16-17 PSI a bit low with a 2.7" pulley ? I think it should be around 18 at least. FYI I was boosting 15.3 with a 3.0" and now runs 21-22 with the 2.6". Do you disable the by-pass valve selenoid ?

 

I dropped a full 1 psi after installing the Corsa. guess your magnaflow is a little restrictive! I also still have the stock air intake and that affects boost as well.
Rob

 

I have a custom mandrel bent 2.5" catback with a Magnaflow straight through 2,5" muffler !

 

I dont mean to harp..but..tHat first part is not really accuarate. Boost DOES matter with a supercharger as that is the point of having one in the first place. Your example is also flawed slightly: Two idential engines with identical pullys..no matter how you slice it..will make IDENTICAL boost levels. Boost is NOT backpressure in the intake...it is PRESSURE in the intake which is rammed into the engine as son as the intake valves crack open.

If I take two engines which are identical in every way except in SC pully size, the one with the smaller pully will be creating more pressure at the intake than the other one. Does this take more power to turn the SC...yes but not as much as you may think..because the extra intake pressure is actually pushing down on the piston during the intake stroke and helping to negate some of the pumping/parasitic losses induced by running the SC at a higher RPM. Now...if both engine's aftercoolers are able to cool the air efficiently, the engine with the increased boost will make more HP and torque all day long.

You are correct in saying that there is a point were it all goes to hell..as every turbo and SC in existance only works well if it is run in its designated design limits. As soon as you run a blower too fast, you will heat up the intake charge too high and lose HP and cause your EGT's to skyrocket as well as many other not-so-nice things.

You are laos correct in saying that an engine with a ported head would make more HP for a given boost level....it will not change the amount of boost in most cases because you are not altering the displacement of the engine but only smoothing out the airflow and eliminating turbulance (porting and polishing makes a more drastic difference on NA engines and is often one of the last things done to a street driven FI engine (expensive for the HP gained).

The trick is air density. Example: 2 engines that are identical excpet that yours is making an efficient 15lbs of boost s(so your SC is not heating up the air too badly at all and your aftercooler is able to bring the intake air temp to about 20 degrees above ambient temperature. Now...I get all mad cause you are faster and I go and overdrive my SC and start putting out 25 lbs of boost. My SC is heating up the air like an oven and my aftercooler is completely heat soaked so my intake temperature is off the charts. The result is that you have a dense charge of air ready to be stufed into your engine and I have tons of boost....but the air is hot as hell and nowhere near as dense as your intake air is. I may make a few more Hp as you do...but not nearly as much as I should be making if I had bought a larger SC that I could run at a lower RPM and a larger / more effective aftercooler setup.

-P

 

the m-62 will allow for 478.96 psi on our engines

 

Peak combustion chamber pressure at TDC may be 478.96psi with the supercharger running at max designed output but that is not the peak manifold pressure.

-P

 

The 2 identical eninge thing I states was off a little. Have 2 identical engine with the same pulleys the one making less boost will be making more power. Why? First since there is a lower delta pressure it takes less hp to drive the blower...second the one with less "boost" is flowing more cfm thru the engine per revolution than the other thereby allowing more fuel to be injected to make more power. Superchargers move cfm of air based on rpm. Since the blower is pushiing a certain cfm of air into the intake manifold per revolution and the engine is using a certain cfm of air per revolution the difference in cfm between what the blower is puting in compared to what the engine is using can be converted in psi. Stock the blower is spinning at less than a 2:1 ratio with the motor...that is why we dont go over 14.7 psi stock. Our blower does 62 cubic inches of air per revolution Our Motor takes 61 ci per revolution. What I'm saying is boost is a function of the blowers output vs the engines intake.

Backpressure really isnt the right term...differential in airflow capacities between the blower and the engine measured in psi is the correct term. I used backpressure because the engine is not flowing as much as the blower...making it a restriction...hindering flow...causing a pressure buildup...effectively causing backpressure from the blowers point of view.

Your theory that the air is pushing down on the piston is negated by the fact that any gain would be eliminated by the extra pumping resistance of having to compress more air.

A ported head, cams, or high flow exhaust should lower the "boost" level. See the gtp forums for examples of this...when they cam a car or add heads or significantly change the exhaust their "boost" lowers. Why? because an engine is a glorified air pump. You have increased the overall airflow of the engine while keeping the superchargers output the same. this means the difference (or delta) in cfm between the two will lower resulting in a lower "boost" level using the logic I provided above.

Selfinfliction and I got involved in a discussion similar to this in a twincharging thread. Engine flow and displacement is constant...blower flow and displacement is constant... turbo airflow is not constant nor is its displacement. But lets assume this is on an engine dyno with the engine stalled at an rpm such that it is at 100% load...the blower is spinning so that it is providing exactly twice the required air per revolution that the motor needs (you will get 14.7 psi manifold psi without the turbo normally under this condition). if you are cramming a steady 14.7 psi into the supercharger from the turbo...you are putting 2 absolute atmospheres of air into the supercharger...it is forcing x2 the air into the intake manifold than it normally would (our s/c just moves air...it does not compress it)...also (you have doubled the amount of air entering the s/c per revolution...s/c is just another air pump like the engine is)...since the engine's cfm consumption is not changing you intake manifold pressure would be 25.4 psi (or 40.1 absolute psi...3 bar...twice the air in the same space with the same consumption). This is why on the twin charged kit they have to run a larger than stock puley size...self infliction...like you told me...its simply physics

The screen is too small for me to read it all...if you disagree with any parts...pick it apart and i'll answer it.

Dan

 

nah man... i know a guy that knows a guy, that has a cousin and his sister is the head engineer for gm performance division engineering sector and he told me that it was g14 classified information.... the m-62 will provide 478.96 psi of boost

 

Ok...now you are talkin my language. I just thought that you were oversimplifying it too much in your previous post and it sorta came out the wrong way. Now what you say makes perfect sense when you explain it in terms of pressure differential and exclude the laymans talk

Most of my knowledge is with turbo systems which act more independantly of the engine than a SC does...so feel free to correct me in the future

-P

 

No problem dude...I'm so used to people giving me blank stares when I go into detail I normally just simplify it. I'm glad it makes sense I spent forever trying to proofread it. Also sorry if I came off as cocky in any part of it.

Dan