has anyone came out with an m90 swap yet? i was talking to mt friend with a gtp and he said that all you would need to do is machine a bracket. but i think that there is more to it than that.

 

nope thats abotu it plus mabe hood clearance and tuning depending on pulley size

 

thats a good point.. but i think that anything is possible. it would be a good power increase

 

IMO I think a twin screw swap would yeild WAY better gains than an m90.

 

True!

 

An M90 would not yield very good gains IMO. It will be spinning slower making it less efficient. It would also be creating more psi which makes it even less efficient. At their peak performance Eatons are 60%-65% efficient. This would be much lower in our application.

 

also consider the cost vs hp ratio im willing to bet there will be only a 10hp gain at most however that 10hp will cost 1000 bucks more at least

a gen 5 ported m90 is pretty damn efficient

dollar for dollar m90>whipple id rather take that 1000 bucks and get a nice set of cams or a ported head

 

I have tried for days to not register and just stay out of these posts until I can get my own ride, but I just have to intervene here. the amount of bad info floating around here is at times scary.


First, efficiency is not the end all. That being said, you need to produce a compressor map showing that at a roughly .5 compression ratio (slightly less than 8 psi) that the M90 is running less efficient than an M62. Until then you are speculating. If it is, it will be only slightly less efficient. A slower spinning blower produces less heat through inefficency. Less heat is good for power.

Second, what an engine needs is air, not boost, to produce power. An M90 moves more air per rotation than an M62. that means it would require less rotation to flow the same amount of air as an M62. Since Roots blowers produce boost by packing air between it and the manifold that means that you will need less boost to attain the same amount of flow. Heat comes from compressing air and blower inefficiencies, so the less you compress it, the less it heats the air. So if it only takes 6 psi to get the same flow as the M62 at 8 psi then you will have a cooler intake charge. Or conversely you could run at 8 psi (or whatever stock is on the SS, i cant remember) but have increased flow at the same intake temp. given the appropriate fueling you would get more power for the same boost. In either case, the M90 is more efficient. And if you look at zzperformance.com they already have underdrive pulleys for the M90, and Im pretty sure they will custom build you a different size for your aplication if you ask nice.

Finally, dollar for dollar, the M90 is going to out produce the Twin screw whipple. Those bastards are very expensive. The twin screw will only marginally out produce the roots at low boost. Where they get their advantage is at higher boost levels where the roots blower is WAY out of its efficiency zone. Once you get to those boost levels though, money isnt as much of a consideration as you have already dumped TONS into your engine.


Hope this clarifies a few things. i may not have an SS, but I have spent years in the GTP scene, and have a very good understanding of roots blowers and boosting in general. there is just too much speculation and junk floating around here from people who just dont have the knowledge yet. With the glutonous amount of M90's floating around it will be a good upgrade in the future once ZZP or INTENSE developes the inevitable swap kit.


BC

 

^^^ Good man! I'm pretty sure that the GTP guys who swapped from M62's to M90s (especially gen 5's) have no regrets whatsoever from having done so. Supposedly the gen 5 M90 is good for 500 hp worth of airflow. I don't know how driveable that would be in a FWD situation, since I'm sure the onset of torque would be outright violent, but I very highly doubt that an M90 swap would not be worth the money... I'd be hard pressed between an M90 and a whipple though, each has distinct advantages.

 

GTP comes with the M90.


The gen 5 is supposed to be taking gtps into the 12's without an IC which was unheard of with the Gen 3.

If the whipple came as a complete kit, was not obnoxiously expensive, and i was shooting fo rthe stars then the whipple would be my choice. If I was looking to see the 11s id likely stick with the M90 or twincharge..

BC

 

well, the series 1 3800 came with the M62, although i forget right now if they ever had the series 1 in the gtp or if that was only the cutlass/bonneville etc... Not a W-body guru by any standards...


and lets not forget... the gtp is AUTO and weighs about 400-500 lbs more than a cobalt SS.... yeah

 

something tells me the cost of the whipple blower alone will cost more then an entire gen 5 m90 kit.

 

thank you for clearing this up. i knew that the m90 moved more cfm's at a lower boost but i wasnt sure if it was reasonable

 

that you are correct on. The series one S/C never saw its way into the GTP/Regal though.


Gtps usually tip the scales at around 3600 lbs without driver, so you can see that it wouldnt take much work on the blowers behalf to make the cobalt haul ass.


BC

 

a newly registered member with intelligence.... this cannot be

thx for the lesson . everything you just said is very agreeable

 

I hate to tell you this, but if you force more CFM in the same amount of space you get higher PSI. The reason there is a measure of PSI is because there is more air being forced in then what could be fit at atmospheric pressure (1 bar). Therefore if you push the same pressure, for this case 12 psi, within the same amount of space, the stock LSJ, you would be moving the same aount of CFM.

The concept of the M90 is to push more CFM to create higher levels of boost. Because the M90 is a larger displacement blower, 1.5L of potential displacement, it would be required to spin slower than it was designed for at that level of pressure. This would allow more air to blow past the blades. Lower RPM + high PSI = brutally inefficient on a roots style blower.

The reason the GTP's really gain from the M90 is because the M62 is too small for the application. The M62 is only designed for a 2.5L-4.0L engine. The 3800 is barely within the limits making the M62 really have to work to make 8 psi on that large of a motor. The M90 is designed for a 3.0L-5.0L engine leaving the blower at it's most efficient range.

A 1.2L twin screw will create 22 PSI with a lower charge temp, while consuming just as much power as an M62 at 13 PSI, and has 90% volumetric efficiency. Even at 30 psi the twin screw has 80% volumetric efficiency. The most an Eaton is capable of is 65%. This means if you have a twin screw and Eaton blower of the same displacement, you would have to spin the Eaton faster to get the same CFM movement as the twin screw. In actuality the 1.2L twin screw moves more CFM than the M90 (1.5L).

If you want to see proof check out the book "Supercharged!" by Corky Bell (click for a link). It has lots of useful information.

 

well your correct and wrong at the same time.

the Corky Bell book was printed a few years ago and for the original gen 1 eaton blowers that were made in the late 80`s had efficiency levels in the 65 % range

well its not 1989.......its 2006 ....17 years have passed and there have been GREAT advances in technology Eaton Corperation has spent millions of dollars in R+D of those years to produce a more efficient supercharger comparing a whipple to a eaton blower made 17 years ago isnt exactly comparing apples to apples

truth is noone will know what the HP difference is between a NEW gen-V m90 Eaton supercharger and a whipple are until there is a back to back dyno comparison, what is known however is that a whipple will cost between 500-1000 dollars more then a m90...

 

The book was published in 2001. Unless he used old info, the Gen V or at least the Gen IV should have been out by then.

 

im sure it wasnt written the same year it was published and i didnt mean to imply that it was written in 1989 but i do know that it was written a few years ago prior to the newest technology, what im getting at is that the new gen V`s are more efficient then the older models.

 

Very true, but they still use the concept of the roots blower which is not designed to run efficiently in high boost applications. I will admit that Eaton has advanced their blowers by leaps and bound over the traditional roots, but it still lacks when compared to the twin screw. Whipple has done its fair share of design enchancements as well.

None the less we will have to wait until both swaps are released to get real world results. My money is on the twin screw.

 

but will it be cost efffective is the question....something tells me the answer is no

im willing to bet it will be 1000$ more....1000 bucks for me will cover new forged wiseco pistons and installation

 

There are elements of truth to what you say, and inaccuracy. Density is also a consideration in pressure. You can fit more of a dense gas into a given space than you can a less dense gas. Heat makes a difference in that density. If you are spinning the blower slower the heat generated will be less, allowing for a denser charge. The density of that charge is going to inherenetly increase the flow of the engine, allowing for greater flow at the same pressure.


You are operating under the assumption that if you were to switch to an M90 that you would stay at the same output as the M62 you replaced. What would be the point. You can now flow more CFM at a greater efficiency with less blower generated heat, why would you stay at the same output. If we are talking about staying at the stock power levels then you have a point. However if you can get increased flow at greater efficiency through an M90 why would you hamper it by trying to stay at stock power output. It would be pointless. Not only is the blower running at a thermally more efficient level, but the fact that you dont need to spin it as fast would give you gains in parasitic losses.

The GTP never had a blower smaller than the M90. The M62 was found on the series 1 S/C bonneville. Just splitting hairs.

I'd love to see the compressor chart that showed a Twin Screw at 90% efficiency at any range.

Nonetheless, if you are shooting for a motor that is capable of using 22-30 psi then by all means get a whipple. im not ragging on them. If you are going to build a motor capable of those pressures, with a fuel system and tranny to take that abuse, then spending the cash for a whipple, plus adapating it to the motor, is just another bill. For the rest of us though that is an EXPENSIVE blower. ESPECIALLY when you can find an M90 for next to nothing. HP is an matter of how much air you flow, not how much boost you have. A 2.0L motor making 350hp is going to be flowing ROUGHLY the same amount of air as a 3.8L engine making 350hp. If you can flow that amount of air at a lower blower RPM why wouldnt you? The parasitic loses from spinning the blower alone, plus the gains seen from lower blower temps, would make the M90 a better choice than a M62.

Im not at all saying that an M90 is a suitable swap for a stock or near stock car. But if you are going to be pushing the limits of the engine, or going beyond the limits on a budget, the M90 is an excellent candidate for a blower swap. Its inexpensive, common, roughly the same dimensions as the M62 with similar hardware. ZZP makes a M112 hybrid kit, so its expandable. The whipple is nice, but unless you are out to make a unique or very highpower motor its just not, IMO, worth the cash. Not when M90s are so readily available.

As for the Corky Bell book. That guy is a genius. That being said, if it is simialr to "Turbocharged" then it is out of date. Just because it was published in 01 doesnt mean that it was written then. It could be that there is an increased demand for the book, requiring another production run in 2001. Then again it may not be out of date at all.




BC

 

First off, I want to thank you for bringing an intelligable and respectful arguement. There are few and far between here lately.
I was just arguing your example of using the M90 to push 6 psi to make the same gains as the M62 at 8 psi. The pressure is a result of more CFM in the same amount of space, so lower psi in the same amount of space is the result of less CFM. In the case of the LSJ it the M90 would be spinning too slow to be efficient at those levels. In higher levels of boost the M90 would be more in it's element, but still fighting more pressure than it was designed for speed of the RPM. It might also result in a slight lag at the lower RPM range.

oops. I knew that but for some reason still typed it. Oh well like you said splitting hairs.

I'm sure that you are aware that Intense is going the route of the M90 and that they are all about pushing the motor to the outer limits. The reason I'm fight the M90 so much is the fact that people believe that it will take them to the next level of performance and I don't think that they are only intending to reduce the charge temp for the levels power they are pushing with the M62. Like you said the twin screw would be most effective in the 22-30 psi range, which is where people appear to be wanting. At least those that are talking about the M90 being better than a twincharge setup. For those just looking to stay in the 18-20 psi range with lower temps then the M90 should be the best bang for the buck and safer than over taxing the M62 like many already are.

Normally if they publish a book more than once they list all the years that it was published. Bell's book only has one date in it and he shows how to supercharge a BMW Z3 which wasn't released til '96 and the Grand Prix got the M90 in '97. So I think it is fairly up to date, although Eaton has made some advances since as well as Autorotor and its off shoot companies.

 

Thanks. Its nice to have a discussion than isnt a pissing match.


Right, and the more I thought about it, the more I began to agree with you. I think though, that once you start getting towards the power output of a stock GTP, 240hp, the M90 will be in its element up to around 350-400 hp. At those levels the LSJ will be flowing roughly the same amount of CFM as a 3800, as air makes power, not boost. At that point you will be getting more flow, at lower boost (due to lack restriction from the physical movement of air through the engine) with less heat. thats where the M90 would shine.






I wasnt aware that Intense was going that route yet, but I knew eventually they or ZZP would head that way. Im sure that those who want to push the limits of their engine and pocketbooks will go the Twin screw route. My guess though is that the majority of the really fast S/C cobalts that we will see in the future will be M90 or M112 hybrids. The 112 versions wont be very daily drivable, but the M90 cars will likely the the big guys on the street. The biggest problem with the whipple is the cost. Sure they will be more efficient, but the M90 has worked well in ported form up over 500 hp. Will be interesting to see.


BC

 

It deffinatly will be. I can't wait.