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Quote:
Originally posted by WERK-I
350Hp930,
I was looking at your stock versus modified gear charts. Are you just changing the R&P?
Yup, the wonderful 8:39 R&P from andial.

Old 05-16-2005, 03:20 PM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #201 (permalink)
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If you're interested in flow numbers for Carrera manifolds, I posted a thread about that here, in case you didn't see it:

http://www.turbo911.org/forum/forum/forum_posts.asp?TID=1126&KW=extrude

I took stock Carrera manifolds and sent them to Extrude Hone, and after a couple swipes they came back with 285 cfm +/-1 cfm runner to runner. It appears that your numbers are higher than mine, which may be because you flowed them at something higher than 25 in H20. I haven't looked back in your thread to investigate. Given how much was done to mine, I'd be surprised if there are any stock-configured Carrera manifolds that flow much better than mine do. The Extrude Honing process is pretty impressive. Of course, the only fair way to compare is to flow them on the same bench with the same operator.

About your change to an 8:39 R&P: If you're satisfied with using just 2nd though 4th, it's a good solution, I think. For a track car, it makes 4th a more usable gear. Problem is, the spacing between the gears, which is fairly distant, isn't improved, and it makes 1st almost worthless (especiallyin your car, where it will just be a tire smoking extravaganza). Also, the strength of the 8:39 is lower than the 9:38, though I'm not sure how significant that is. I chose to do something different here; I stayed with the bulletproof 9:38 R&P and regeared my stock 930 gearbox to the following ratios:

1st 19:33 (taller)
2nd 23:30 (stock)
3rd 26:26 (shorter)
4th 30:23 (shorter)

This makes for a close ratio gearbox, or an "active" gearbox, where all four gears are road racing gears (which was my goal). If I recall, it will rev out in 1st gear at 72 mph. That makes for some clutch slipping to get it going, but it's not objectionable to me (of course, if drag racing is your thing, it won't work). It revs out in 2nd at around 95, third at around 125, and fourth at 161 or so. This choice of gears isn't for everyone, but it should be right on for my purposes. It's essentially the same gearing as a 915 gearbox, but without 1st gear!

The cost of doing this is not trivial, but neither is an 8:39. I'd say the cost is equivalent. If you've got your box apart, and are doing your own work, that certainly helps. I got some used factory 962 gears (1st and 4th) for $650 each or so, and a new aftermarket 3rd gear for $750 or so, if I recall.
Old 05-16-2005, 03:58 PM
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Just a little off key but any help would be great.
Thank you.

Wastgate ?
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Old 05-16-2005, 04:06 PM
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Thanks for the link Rob. Just in case there might have been a leak with my flow apparatus on runner number 2 I am planning on testing it again but overall I am happy with my results even if that one runner really is a bit high.

I also know I will be happy with the new R&P since one of my only complaints about the 930 tranny was first gear being too tall for fast launches and my need to perform better on tight auto-x courses.

The 15% gearing reduction should be a perfect solution to those problems and having my top speed limited to 170 doesn't bother me one bit.

I am actually happy with the ratio splits between the gears since I am hoping that my mods will give me a pretty fat torque curve between 3500 and 6500 RPMs and the current gears will be perfect for keeping me in that range as long as I am moving faster than 20 mph or doing a 3K RPM launch.

I know it might not be the best solution for a track car but I am trying improve the car's low speed performance.

The car used to clean up its class at many a auto-xes but I had a few tough contenders to deal with. With lower gearing and more torque I will stomp my competition and hopefully end up with some respectable quarter mile times to boot.
Old 05-16-2005, 05:40 PM
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Sounds good to me. It's all a matter of how you use your car and where you want to "give it up" when you're limited by only 4 gears. I think you'll find with your power, though, that autocrossing will be an exercise in self restraint...
Old 05-16-2005, 06:04 PM
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LOL, it always was but now I can use some more of that restraint down around 25 mph.
Old 05-16-2005, 06:38 PM
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BTW Rob, adjusting your flows for 28" would convert them to about 298 CFM.

Last edited by 350HP930; 05-16-2005 at 06:51 PM..
Old 05-16-2005, 06:49 PM
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I'm planning to make the R&P change on my 4 speed also. At this point it's the last item in my rebuild/EFI project.

A G50/50 would be the ultimate but there's too many mods and dollars involved with it.

I talked with the folks at Rennsport Systems about the R&P change and they recommended changing the gears instead. The cost would be about half the cost of G50 upgrade so I'm back to the R&P. So far the Andial is cheapest I've seen. The 930 with the 8:39 R&P closely matches the first 4 gears in the G50/50 which can't be all bad.
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Old 05-16-2005, 07:11 PM
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Yes, I looked at the numbers and $$$ for both paths and chose the R&P option hands down.

Relatively cheap and effective. I got mine for $1050.

Last edited by 350HP930; 05-16-2005 at 07:20 PM..
Old 05-16-2005, 07:18 PM
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That's why I wait til the last minute to make the final decision on any part of this project. Hopefully I'll come across a better deal on a part to jump on but if I don't hopefully I will have gained more knowledge from this site or another to make the best cost or performance decision.
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Old 05-16-2005, 07:40 PM
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Taking one's time has its advantages. I have saved thousands by not being in a hurry for what I need. Then again project creep allways gives me creative ways to spend my savings.

I've got my turbo and intercooler options picked out but will wait till the last minute to purchase them.

Good things come to those who wait.
Old 05-16-2005, 07:55 PM
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Hey guys I have a G50 turbo and if my money tree were to sprout I would go longer with 1st and close up the rest. With a little slip I can start pretty easily in 2nd and 5th is nice for hwy economy runs. Which leave 2,3,4 for the majority of spirited fun.
My point is don't get to caught up in the 5 spd thing.
Old 05-16-2005, 08:00 PM
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It amazing how a little engine rebuild and EFI project has gotten so out of control. With the engine it became a while I'm in there thing with new rods, pistons, and cams. Since the engine's out I figured I should replace all the fuel lines, the rear suspension bushings (Elephant), and new torsion bars. I'm into five figures and I still haven't bought a turbo, intercooler, ECU, or ignition.

I talked to Bell intercoolers and looked at a design they had but I didn't like it. Bell seems to be the cheapest and fastest way to go, but I'd like to have some flow diverters inside the end tanks and I'm not sure if they're willing to put them in. I may have to make my own with their core.
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Old 05-17-2005, 04:48 AM
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As you mention endtanks are important, but with well designed endtanks diverters become almost unnecessary.

For the sake of good flows and efficiencies I will be going with a side flow intercooler with the following endtank configuration.



Old 05-22-2005, 07:19 AM
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Hmm I have seen that intercooler before Marco knows what he is doing in that area no doubt. I will post some pics of mine when it is done....Marco is building mine as well.

Eric
Old 05-22-2005, 09:45 AM
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Marco wanted a bit too much for fabrication so I was planning on getting it fabbed by bell instead.
Old 05-22-2005, 01:46 PM
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Wo ist die Rennstrecke?
 
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Speaking of Bell, during a drive here in ATL yesterday, my manifold air temp sensor showed 22 - 23 C all day. This included a 1 degree rise under heavy boost use. For your info, the outside (ambient) temp was 75 degrees F - about 23 - 24 C. I have to say the more I drive the car with the Bell IC, the more I like it. By taking the front to back design and the big core (4"), I have very little pressure drop and temps are just right. It would be interesting to know what the pressure drop is comparing side to side and front to back, then compare temp drops. I like Marco, but I really like the Bell.
Old 05-22-2005, 07:43 PM
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Don how much was your cooler from Bell if you dont mind me asking
Old 05-22-2005, 07:52 PM
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Wo ist die Rennstrecke?
 
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A little over $1100 delivered...
Old 05-22-2005, 08:07 PM
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there pricing sure is nice. What are the end tanks made from?

Old 05-22-2005, 08:14 PM
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