ALFAGTV6.COM

Chevy Cobalt - 2.0L 4cyl 16v supercharged, factory says it puts out 205hp stock

http://www.chevrolet.com/cobalt/

Greg we don't doubt you can do it, how about chucking on an MP90?

ROCK ON
R~R

Just for the record the Cobalt's 205 horsepower rating is massivly under rated. This is probably to make the car insurable for its target customers. It uses a Saab engine with a M62 supercharger and a very good intercooler and actually puts out about 220 to the wheels and my friend's has a bit more due to an excellent intake giving it 9 more whp in mid range and 6 more peak whp.

It's ability to beat my GTV6 in a 5 mph start drag race is almost entirely due to gearing. I could probably bolt in a 4.10 transaxle and beat it. However I am doing this the hard way as I am still in the keep it original and reversable mode. I am putting in a Syclone intercooler modified to fit without cutting any holes in the car. I am also putting in a digital controller to vary the amount of water injected with RPM. Then there is the special coating on the supercharger rotors to make it more efficient and the high speed bearings enabling it to generate whatever amount of boost I feel I want. However I don't plan to increase the boost on this motor so the bearing won't matter.

The MP90 is not needed and assuming these supercharger mods work out it never will be needed on a 2.5. The increase in allowable maximum supercharger speed will allow a lot of extra boost, more than I will ever use.

Oh, and if all that doesn't work, it's time for Gotech, forged pistons and headers!

Daniel wrote:Ben,
Let me redo that - "Should be enough to keep a few of the local boys (who are not Ben Bishop) honest and then we get to the first corner "

Bwahahahah.
You'd cane me across Neebo without a problem, but somewhere like the run up the ridge to Mapleton would be fun

Ahh Gregor.....

That's what I like to hear!

The blower bug has bitten....

Hey Greg, how do you think an 8/71 would go on the 2.5?

Think the tranny would hold up? Yes I am being a dickhead again!

Put some short gears in mate- you know you will love it-

Oh, BTW, what revs are you stalling it up at? I suppose you dont need heaps, because the torque is there... My engine ends up at around 5500 stall when I race someone... jumps out of the whole pretty nice when you get it right though... you should get some vids for us Greg.

Ben....

Hurry up and buy a wog car again!

Ben, in the stoplight gran prix I try not to attract too much attention so I just start out like normal and once the clutch is out feed in power. On the pre planned drags we start at 5 mph with the clutch out. Of course this is a big drawback with the 3.42 gears at it takes relatively long time to get the revs up unless I light up the tires. I am afraid 5000 rpm clutch dumps are not on my list of things to try out.

I know you were kidding about the 8-71. However just for the record it's way too big. Those things displace around 500 cubic inches. Even with like 40 pounds of boost the rotors would have to turn so slowly on a 2.5 that pressure leakage back to the intake side would result in massive heat. Plus it takes a lot of work to set up a GMC blower. The 2-71 would actually work as far a size goes. However the 71 series of GMC blower were designed to put out zero boost, yes that's right ZERO! Since I want boost I figure its better to use a blower designed from the start for boost.

My wife just got a new digital camera. I think it takes videos so as soon as I get it back together I will take one. I guess that's long overdue.

SydneyJules wrote: Ben....

Hurry up and buy a wog car again!

Isn't it a Woggy enough colour? My dad calls it "Juventus Blue"...

Yeah, but at the moment, its more "Yassu Re" than anything else!

You need a "Giuseppe/Giovanni" car

Actually, Ive decided a big bushy "Mo" could be the way to go for a future look for me...

Greg. Are you using the syclone lower heat exchanger & upper garrett intercooler? I have a syclone myself. If you need more let me know. Many guys are not using those any longer. A/A is most commonly used.
For a 4000lb brick, it can certainly move fast.

The gearbox does slow you down a bit. It's just as strong as most other 80's boxes. I have seen a couple broken pinion gears and a broken second gear. Strangly I have only seen gears break in 1983 cars.

Sort of. Upper Syclone intercooler and no plan yet for the lower heat exchanger. I am figuring on a Motorcycle radiator for the heat exchanger. However I may end up going with a PWR unit instead. There are a few small problems with the Syclone unit that are kind of adding up. It's one of those cases of looking good in theory until I actually put it on the car.

The problems are: 1. The coolant inlets and outlets are in a really bad spot when the intercooler's air outlet is lined up with the throttle body. They can't be moved much or it will defeat the excellent double pass design. I altered them to get them to fit. 2. Connecting that oval shape to the round throttle body is problematic at best. 3. It takes up space I need for the intake system. Eliminating L-Jet would fix this but I am not ready to do that yet. 4. I am not happy with the bracket I made which is sort of a triangle like thing that attaches to the head cover. I can't come up with anything better without drilling holes in something.

All of these problems are minor but they kind of add up. I will work on it more on Saturday. I will then decided to keep it or go with the PWR unit. Keep in mind, it's not just a case of getting it to work, it has to be repeatable and reliable with a reasonable amount of labor.

As a point of intrest it's SO much easier to intercool a Milano. I have a Mitsubishi unit that looks like it's made for the Milano and the Syclone would be an easier fit to as there is more room aft of the motor for those coolant hook ups.

Thanks for the input.
I wanted to clarify something about 0-60 time. Is this 300Hp at the crank or 300HP at the wheels. After educating myself on modifications it appears that you lose an estimated 20% hp through the drive train. Also, I was discussing this with others and we were wondering what is the measurement of an HP. Is this one live horse for power. Now I know this sound really dumb but I did not know how to explain this.
Thanks for letting me know what the defination is.

To come back to the original question!

I visit during the season almost all Hungarian Drag Racing event on the quater mile.
Before I did I made a rough calculation about the possibilities. There is a program called 'CARTEST' which can be parametered quite well and it can simulate a drag race with good accuracy if you set the datas correctly. I checked it with many cars which I have real test of it.
So the result was to my config:
0-100 km/h 5.9s
1/4 mile 14.3s @ 157.8 km/h

What I achieved on the drag strip:
The best result was a 13.914 s @ 159.5 and once I touched the 160, but it was a bit 'goodwilling' measure, since almost the whole bunch was able to run it's personal best during the season at that day. Anyway I felt there was the best grip at all.
Come back to the standard results, they spread between 14.1-14.6s @ 155-158 km/h depends on I'm running on slicks or road tyres and the different surfaces of the tracks. And the differences between the measuring systems (different rollout, etc.)
I have a lot of G-Tech measures, but they are not so accurate and a bit optimistic because it put me well above 160 at the end of the run.
But there is a guy who's got a quite precise device working similar way as the G-Tech but it gets feedback from GPS and the unit also has much stable fastening part and I think less or even not depends on the angle of the car during the acceleration. He measured me and You can find it on http://timeslip.hu
It was a run measured by the official system with result of
60' 2.32s
1/8mi 9.36s @ 124,48 km/h
1/4mi 14.396s @ 156.28 km/h

The guy measured me without rollout
60' 2.61s
1/8mi 9.63s @ 127 km/h
1/4mi 14.68s @ 157 km/h
0-100 km/h 6.47s
80-120 km/h 4.03s

I want to state it wasn't my best run at all. Even not by feeling. But the 0-60 cannot be better than 5.8-5.9 at the best runs.

Let's talk about the config:
It's a 1981 US-Spec car but now it has 4.1:1 diff with LSD and since the US-Spec bumpers have been stolen I use Europeans. So the car now weights around 1410kg on the board with me. It's fully equipped with leather interior but the A/C (It was killed by the time of the new engine arrived )
The engine is a GTA 3.2 24V in its basic form, only the necessary changes have been made until now to fit into the longitudinal layout. But You can see it in the topic about it. It has a free programmable ECU which is not programmed well I think and a not optimal exhaust system. The new ehaust system is under construction now and when it will be ready and maybe some minor changes and/or a set of new cams, I will take it to a new programmer to make the config run better. All in all, I think the engine should produce 240 HP as a maximum at the cranck and produce around 190-200 whp.
The revlimiter is set to 7500.
Anyway the tranny, the shaft, the donouts and the twin plate clutch are stock.

PS: In the previous config with 3.0 engine from a Milano with a 4.3:1 non-LSD it did the 0-100 around 7.4s but it can keep up (or even beat and they reach me then! ) 'til the end of the 2nd gear (90 km/h) with modern cars rated at 6.7-6.8 (Civic TypeR, Saab 9-3 Viggen)

I forget to give the tyre types.
The road tyres are Yokohama A520 225/45 R16
The slicks are Michelin N2 19/63-17

Thanks for all the input on my topic. So I have decided my plan for my first engine.
I am going to swap with a 94 164Ls engine that is going to be built by Jungle Justice. It is the glenwood brand and will have 270hp. With this engine and stock 82 GTV6 drive train what would one estimate the 0-60 limit & 1/4 mile time to be?