C20get - C20let pistons and rods quesitons

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C20get - C20let pistons and rods quesitons

Post by M I N I O N »

I've had a little fun with my balanced fresh bottom end in my sunbird. I was saddened to say the least to find that the stock rod bolts could only handle around 250hp so I have run no more than 10psi from my 35psi capable turbo and have not touched my nitrous. I'm troubled. I'm ready to park it again (yah... fun couple of days) and build the bottom end up fully with nothing but forged internals. I'm going for broke this time around with the bottom end and further building the head as well to rev beyond 7000rpm with the C20get.
For the bottom end I am looking to get custom 7.8:1 Wiseco forged pistons and foreged H-beam rods as well. I have done some reading on people swapping in C20let pistons and rods as an improvement over stock. Rather than going with custom rods, is there anything stopping me from using the forged rods that you can find on e-bay for a C20let? Do they use the same narrow bolts or are they a little wider than the C20get? If I get my custom pistons made for a C20let and use the appropriate wrist pins, ect.. is anything stopping me?

Other things will include a custom knife-edged crank, clevite 77 bearings and a bunch of other pretty trick things. :badgrin:
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Post by Efratech »

you mean factory LET rods? they're 'only' capable of holding about 350whp or 24psi of boost on ARP rod bolts (almost breaking :lmao:)

go for aftermaket rods.

That will be a nice spec bottom end.
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Post by exist3nce »

Efrain A. wrote:you mean factory LET rods? they're 'only' capable of holding about 350whp or 24psi of boost on ARP rod bolts (almost breaking :lmao:)

Wow thats quite a bit for the stock rods. I was thinking about swapping those pistons / rods into my engine if I decide to push the power higher.
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Post by M I N I O N »

Oh I think you took it wrong. I am not putting factory C20let rods in my block. I am planning on putting aftermarket C20let rods into my block with aftermarket C20let pistons to custom specs. This way I get the floating wrist pins, but I was also wondering if the bolts they came tapped for were thicker than the C20get rods or should I over-size them and use bigger bolts. Maybe the ARP in standard size are thick enough for 600hp?
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Post by PrecisionBoost »

Go here.... http://www.importperformanceparts.net/

Pick Opel and go into rods.... the TOGA rods are pretty decent and very cheap... ARP2000 bolts...not sure about thickness of the bolts but they do rate the rods for 600HP and 8,000 RPM

http://www.arrowprecision.co.uk/ has some of the nicest rods I've seen for the C20LET.... but they are expensive

http://www.arrowprecision.co.uk/details.php?id=66149

I talked to them and they really want to push into the north american market.... they offered me a set for $1100 USD... but I turned them down.

Sure they are nice.... but Pauter will make them cheaper ( around $650 ) and their quality is great.

I'm not sure why you'd want to drop down to 7.8:1 .... most of the high power C20LET's seem to be running around 8:1

ARP does make a rod bolt kit for the C20GET rods (I have two sets) .... not sure where they break.... if the rods are debeamed, balanced, polished then shotpeened with ARP bolts I'd say that 400hp is possible....perhaps more.

Certainly I think it would be pushing it to hit 600hp.... and I have to think a stock tranny to be incabable of taking that kind of power.

Hell.... 350hp would probably need some serious tranny work.... are you running an auto or manual?? If manual Getrag 282???

Ned Southwick had decent luck with his built up TH125C (3T40) but I have to wonder if the Getrag 282 is up to the task.

By the way.... I also own an 87 Sunbird GT and I use to frequent many J-Body forums... as well as the LT3 forum... so I have some experience with the sunbird.
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Post by GsiTurbo »

And for some custom forged low compression pistons, talk to Kinkyllama - he can set you up with custom set for the 8V motor. Remember that 'off the shelf' pistons for C20LET will have valve relieve cutouts, which you really do not need.

Tom
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Post by PrecisionBoost »

Yes he will..... he's going with the 16V head.
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Post by M I N I O N »

[img]Yes%20he%20will.....%20he's%20going%20with%20the%2016V%20head.[/img]

Eh, that is still debatable. I'm only going to swap to a 16v head if I can't break 500whp without nitrous using the 8v head at 30ish psi. I don't plan on it really.

JFWI, the transmission has been swapped to a getrag. As of yet there have been no trans modifications, I know the getrag has held 400+hp in the stock form before. Ther is no way it can handle 600+ with slicks. even if the diff didn't pop, the axels would. This trans has all the same gears as an NVG T550 which has the same "abuse handling" reputation. I'm looking for a shop that may have built those up for quad 4s back in the day to find out what parts are interchangable since internally they look the same.
Either way, it will be a while before the car runs down the track so I'm not real worried about it right now. Ned's luck with his built 3spd has a lot to do with the fact that that is a common transmission to built up for power or performance usage. He ran mid 12's last I checked, could have been deep into 11s with a 5spd. I'm just worried about axels.

Thanks for the links. Is it just me or is $350 a little cheap for forged H-beams? Anybody ever used them? I'm not trying to cheap out on my rods but if these are good quality at this price.... count me in!!!!! For pistons, I'd rather use the newer designed wrist pin which is why I want to swap to c20let rods/pistons. I want a "not so off the shelf" compression ratio so I will just ask for no valve reliefs. I want to run 7.8:1 to give me the ability to run a little more boost on pump gas than most are running, which calls for a larger turbo. Since I have the nitrous spooling system, it should balance out well.
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Post by PrecisionBoost »

I don't know if Tom cares if I post this... but he recently picked up a set of those TOGA rods.... he had the owner of an extreemly reputable performance engine shop take a look at them.... he said they look very good and was very surprized that they were that cheap.

Given they actually say "600HP and 8,000 RPM " on the site..... they must be capable.... or that would be false advertizing.

IPP is part of flatlander racing..... it's a huge company..... so I'm sure they wouldn't throw out specifications unless they were sure it handle it.

I think I'm going to pick up a set or two or three.

As far as Ned.... ya... I'd agree he's lucky.... and crazy at the same time :)

With an Auto tranny you have the cushion effect from the torque converter.... a 5spd might be a little quicker but I have to wonder if a Getrag 282 will take that kind of power with slicks.

I'm trying to remember..... it's been a while since I was into the J-Body stuff.... there is also an uprated version of that tranny called Getrag 283 found in a couple different cars... think it was the supercharged Bonnyville SSE.... it's basicly a 282 that's been fixed up to take more power.

I think it was mated to the 3.8L Supercharged engine.... so I'm not sure if the bellhousings match up..... didn't get that far in my research...... but I know there was a guy pushing 600hp with his turbo 3.8L Bonnyville.

For myself.... I'm looking at the new Getrag F40.... the design is very impressive.... it should be one of the strongest Opel engine compatible transmissions they've ever made ( suppose to be stonger, lighter and smoother than the F28 )

You could probably get this F40 (6spd) into your Sunbird with some creative tranny mount work.

In the USA it can be found mated to the 3.9L V6 as well as the Saab turbo engine.

In Europe it can be found mated to the Z20LET/LEH .... which is our engine.

I belive they made different bell housing castings for different engines.... and from what I've found the bell housing plates also house a bearing or two.... so it's not the easiest thing to convert.

My hope is to find out if the Saab turbo bell housing is compatible with ours..... if not I will be trying to either import the European F40 or purchase the bell housing section from a dealer in Europe and convert a north american F40.

My fingers are crossed that they made two bell housings... one for all the different 4cyl engines and one for all the V6 engines.
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Post by PrecisionBoost »

Here is some good info on the F40.... http://www.daewootech.com/forum/viewtopic.php?t=6502
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Post by Mr_Efficiency »

I know the bonevile tranny your talking about it also came in the grand prix and such, but the bell housing is diffrent, but all the internals are the same so theoretically you could just swap out the internals into the sunbird casing, I've been looking into this a lot recently cause i'm in the same boat, I was told teh getrag 282 will only stand up to around 350 hp in stock forum and i'm looking to be making around that if not a little more and theres nothing on making thema any stronger that i can find. And as far as i know that is the strongest tranny GM makes that will bolt up to our blocks.
also i'm pretty sure teh SAAB tranny wont fit our cars, I know for a fact that the ecotec motor has a diffrent bel housing pattern and i think thats what they use for a turbo motor in the saab's but i dont know for sure, i really hppe not cause a six speed would be awesome :D
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Post by PrecisionBoost »

The 6spd F40 is also used with the Z20LET.... which is our iron block... I just need to find out if the bellhousings are completely different or not.

If it is different I will have to either source a bellhousing from Europe/UK or get an entire F40 from Europe/UK

I wish I could find a good picture of a F40 attached to a Z20LET..... for some reason I haven't found anything.... where as I have multiple pictures of the F40 connected to the 3.9L V6 (North america) and the Saab 9-3.
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Post by Efratech »

chris@PrecisionBoost wrote:The 6spd F40 is also used with the Z20LET.... which is our iron block... I just need to find out if the bellhousings are completely different or not.

If it is different I will have to either source a bellhousing from Europe/UK or get an entire F40 from Europe/UK

I wish I could find a good picture of a F40 attached to a Z20LET..... for some reason I haven't found anything.... where as I have multiple pictures of the F40 connected to the 3.9L V6 (North america) and the Saab 9-3.
Have u checked with the guys at http://www.z20let.co.uk/ ?
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