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I am thinking of changing the gears in my manual transmission and was wondering if anyone has done it. With all the power I'm running Id like to get closer to say the Corvette ratios in the trany other then maybe leaving 1st gear alone for getting off the line. :)
 

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No, no one has changed gears in the trans other than with other stock gears.

Assuming you have the skills to do internal transmission work (which is unlikely for most) where would you get a custom set of gears? you are willing to pay $2000 bucks for a set of gears for a slight ratio change? What would be the point of this modification? and why are you unhappy with the stock ratios?

You refer to the "corvette ratios" (which are many depending on year) and the rear end gear is different in the corvettes. so I don't understand why or how you would accomplish such a task.
 

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No, no one has changed gears in the trans other than with other stock gears.

Assuming you have the skills to do internal transmission work (which is unlikely for most) where would you get a custom set of gears? you are willing to pay $2000 bucks for a set of gears for a slight ratio change? What would be the point of this modification? and why are you unhappy with the stock ratios?

You refer to the "corvette ratios" (which are many depending on year) and the rear end gear is different in the corvettes. so I don't understand why or how you would accomplish such a task.
I have to get it back on the Dyno for the final tune but am running pretty close to 400hp @ 2400 RPMs First gear is a little to low as is second. Corvettes and mustangs can make it to around 56-57 in first gear before ignition cutout. With my short tires I am running the same ratio as 4:11's and am in 3rd gear before 60. I want to maintain the quick take off but with factory gearing but it hits the rev limiter @ 167mph. I some other things to do (it's a secret) but am going for the first Saturn Sky to hit 200. With some more work and gearing I'll make it :) heading to see the boys at Hennessey tomorrow to talk about some things. :) as far as the work I'm pretty sure I can do that myself.:thumbs:
 

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Discussion Starter #5
Well ddm has an entire tranny swap so what gearing does that other tranny have?
I'm not sure. I'm going to look up what other vehicles that use the same trany as ours like the Colorado pickup or the Cadillac CTS and see if those have different gears as what's in the Sky.
 

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goodluck with that goal

on a stage 2 SC car you better rent a few miles of runway to reach that goal... personally I think the motor would go pop before that happens. Too much load for too long of a time.

I would think the t56 swap would be a good idea... as well as some serious cooling mods.
 

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Discussion Starter #7
goodluck with that goal

on a stage 2 SC car you better rent a few miles of runway to reach that goal... personally I think the motor would go pop before that happens. Too much load for too long of a time.

I would think the t56 swap would be a good idea... as well as some serious cooling mods.
Thank you.
I know this would be a very big undertaking but you need to set a goal before you can start working towards it. It is very hard to break the 200 Mph mark due to increased drag proportionate to velocity/speed. The Hennessey 2014 Corvette Stingray is still normally aspirated but does have power mods and tuned to 700 HP and stock weight is 3300 pounds. That being said if the drag was equal the sky would need 641hp. It all gets down to power to weight ratio and drag. The Mazda Furai concept car is 450hp weighs 1488lbs with a drag coefficient of just .36 but even with that top speed is only 180. Top speed depends on several things not just horse power. Also yes my signature says stage II but in fact I have more power then a stage III. The SC is fully ported with a 21/2 inch pulley so I'm pumping pretty close to 15 psi of boost. The porting made a huge difference. The torque is unbelievable. :)
 

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Thank you.
I know this would be a very big undertaking but you need to set a goal before you can start working towards it. It is very hard to break the 200 Mph mark due to increased drag proportionate to velocity/speed. The Hennessey 2014 Corvette Stingray is still normally aspirated but does have power mods and tuned to 700 HP and stock weight is 3300 pounds. That being said if the drag was equal the sky would need 641hp. It all gets down to power to weight ratio and drag. The Mazda Furai concept car is 450hp weighs 1488lbs with a drag coefficient of just .36 but even with that top speed is only 180. Top speed depends on several things not just horse power. Also yes my signature says stage II but in fact I have more power then a stage III. The SC is fully ported with a 21/2 inch pulley so I'm pumping pretty close to 15 psi of boost. The porting made a huge difference. The torque is unbelievable. :)
No offence, but 641hp in a kappa motor has never been done to this day. You wont get there with a blower on a 4 cyl. just not going to happen. You are talking about 300ish hp. you need over double that to reach the goal by your own calculations (assuming the drag coeff of the new vette is the same.. which is a stretch at best.)

Even if its a Port injection motor, you are talking thinks that are completely foreign to the kappa world. Multiple fuel pumps, increased fuel line sizes, CDI ignition boxes, etc.
 

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Discussion Starter #9 (Edited)
No offense taken. Your not getting what I'm taking about. I'm not saying the Sky needs 641 hp to reach that speed. Only if the drag was the same as a Corvette. I've been to 155 with lots to go so the Sky's have less drag then people think. The flat back window causes almost all the drag on the Sky which I'm taking care of. You may not need 641 to reach 200 in a Sky. I'm thinking 500 or even a little less would probably do it with proper gearing. As for the 2.4 reaching that HP there have been dragsters with 4 cylinder Ecotecs that have hit 1300hp, google that. As for the porting I'm only talking the SC not the engine all though my intake and exhaust will be ported. Fully ported superchargers are way more efficient then a stock blower and the MP 62 is capable of running 21lbs. Before I do this I will have a built and totally balanced 2.4 that will run like a Swiss watch. :)
 

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hope we have some provisions for a motor build as well. 2.4 wont take the power you are discussing. Pistons and rods will need replaced for sure... which entrails motor pull, tear down, machining, rebuild etc.

Discussing a rail drag car in the same sentence with what you intend to do is not even in the same ballpark. Two totally different events.

I wish you the best of luck, however I would talk to someone you trust on kappas to explain what you are getting into. I feel you are talking about a 25k investment to reach your goal at the low end if you did your own work, which doesn't sound like the case. And I just don't see the blower getting you where you need to go, but I could be wrong.

I hope to see a build thread in the near future on all these things :)
 

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Discussion Starter #11
hope we have some provisions for a motor build as well. 2.4 wont take the power you are discussing. Pistons and rods will need replaced for sure... which entrails motor pull, tear down, machining, rebuild etc.

Discussing a rail drag car in the same sentence with what you intend to do is not even in the same ballpark. Two totally different events.

I wish you the best of luck, however I would talk to someone you trust on kappas to explain what you are getting into. I feel you are talking about a 25k investment to reach your goal at the low end if you did your own work, which doesn't sound like the case. And I just don't see the blower getting you where you need to go, but I could be wrong.

I hope to see a build thread in the near future on all these things :)
Sir apparently you don't know who I am or have ready any of my posts or threads. The people that do know me know I do all my own work. Yes a build is intended with rods, head bolts, pistons and maybe cams. Everything will be matched balanced. All that I will do myself but if there is any machining to do Ill take it to my machine shop to do. The bottom end of the 2.4 has four bolt mains and rated for 550hp. I think once built and get the supercharger on and my meth injection I'll be at around 450-475 and be strong. Very few engines will withstand 7000 RPMs other then a F1 engine. That's the reason I wanted to change some of the gearing inside the trany so it would have more of a gradual increase in speed instead if just getting into 4th and putting the peddle to the floor and waiting. If your running high horsepower the Kappa's transmissions are geared to low. I haven't seen anyone that has been on a long enough road or track that could just let the car go to see what it would do. I think a lot of people would be surprised just how fast these little cars will go.
A dream maybe, but without dreams you can't set goals :)
 

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All im saying is that its a lot more than power alone. (and the power will be difficult on this platform as well) You will be not only fabbing tons of custom stuff, but you will need custom aero pieces to keep the car planted. Here is what happened to Jason at a half mile event this summer at 187mph:

https://www.youtube.com/watch?v=TqzUoeL1vXk
 

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Discussion Starter #13 (Edited)
All im saying is that its a lot more than power alone. (and the power will be difficult on this platform as well) You will be not only fabbing tons of custom stuff, but you will need custom aero pieces to keep the car planted. Here is what happened to Jason at a half mile event this summer at 187mph:

https://www.youtube.com/watch?v=TqzUoeL1vXk
Oh yes I am aware of how air pressure effects a car at speed. I already have the RK ground effects and am very pleased with them. The car starts sucking to the ground at around 30 mph and increases as speed does. I know at 150 the car is really stuck to the road. Hard to believe until it happened to me but with the ground effect on even driving around town if I drive over a totally smashed and flat soda can it will suck it off the road and bounce along the bottom of the car so I try not to do that:) I'm still going back and forth on a rear wing. That's one of the things I'm going to Hennessey today to talk about. :)
 

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Didnt the 2jz sky lose traction at 180 with no wing? He has 800hp so your goal is stupid. He could just beat you.
 

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I've been to 155 with lots to go so the Sky's have less drag then people think.
Really? Less drag than the factory engineers think?

From such an engineer (who seemed to have exact test data as to drag):

Using a non-spoilered Convertible Solstice as a baseline:

the coupe is about 50 "counts" or 50 thousandths less drag. This means it is -0.05 less Cd. It has "in the ballpark" similar front and rear lift coefficients as a Convertible Solstice.

The addition of a spoiler to a convertible drops the drag about half that, on the order of -0.025 or 25 counts. It also miraculously reduces rear lift at the same time.

I am not allowed to share exact drag/lift coefficients, so these are all relative.

Also, there is very little to no difference between the SKY and Solstice in similar trim, and very little difference between n/a and turbo versions. Major changes are the presence or absence of a spoiler, and whether you are a coupe (the slipperiest of the Kappas). The integrated spoiler at the rear of the coupe is on purpose.

Top down on the convertible with windows down INCREASES the drag by 50 counts or 0.05.

In practice, a top speed for an Opel GT or Solstice GXP 'vert with wing is about 143 MPH. I have seen top speeds of about 147-148 MPH for a Solstice GXP Coupe in comparable conditions.
So if you've added 10 mph over stock GXP converts, you have obviously increased your power from that level, but the convert with a Cd of .45 is a relative barn door even though it doesn't look it, and you would need far more power than your engine is capable of to get the car into the area of even an older Corvette (C5 coupe Cd = .29)

In fact the power needed goes up with the 3rd power of the speed increase, so you'd need 700 BHP or a bit more to hit 200 mph, assuming you could keep it on the ground at that speed.
 

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700 HP is gonna mean a custom forged crank and a different block, LSJ racing block or maybe the Gen 2.5 LDK/LHU block or a Gen 3 LTG.

I would ditch the blower for a big twin scroll EFR, I don't think its gonna flow enough air, you talking 100+ LBS/min of air!

I have a custom forged 2.5L crank and I don't think I'll hit close to 700 ever.

And your gonna need a custom hard top maybe like Norms SKY Coupe top, I've been in a Opel GT flat out on the autobahn and it felt and sounded like it was about to rip apart. The hood has a lot of lift and the fenders aren't well supported and started rattling.

That's probably gonna mean a V-Mount extractor front end. And I promise you're gonna rip the rear bumper off, it like a big diaper parachute on the back, clean up the air flow there with a full under body aero-panel.

But I probably don't know what I'm talking about....

I hope you get it all figured out, start a build thread and keep us posted!

--Christian
 

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Discussion Starter #18
Knowing more about your goals, I think the only solution is going with a t56 conversion. gives you an extra gear and will be plenty strong to hold the power you will need to make.
You may be right. I do like the gear ratios in the T56. Only have to go to 6200 in 6th to hit 201. Have read about swaps but not in detail. I would assume a adapter plate, some kind of tail shaft support and a different length drive shaft. I will look into to that though.
Thanks for your ideas.
 

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