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I have a 17 premium with 87k miles, the car was built by SP Engineering in Cali sometime in 17, appears to be quality work on a very conservative tune. Its FBO E85 and the car has been fun for the 3 months I have owned it. I had it tuned by Hydra motorworks here in WPB FL and its 615/610. My plan was to upgrade the turbos to AMS Omega 9 turbos, Shep 2.5 trans and the other supporting mods to make 800/650. I am now realizing that with that many miles on the car and the fact that the motor will already be out I might as well go ahead and forge the internals and go for 1000/900. The questions I have are I have already bought the Omega 9 turbos, will they be good to what Im trying to accomplish and can I use the factory head to do what Im looking to do?
 

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Factory heads will have no problem supporting that kind of horsepower. However, if youd like to rev it out into the 8k range, go with a Ferrea valve springs to keep things happy...might want to throw some cams at it too. Porting is not necessary at that power level.

Truth is, you're throwing a fair bit of money at it. Overbuild it once and never look back. That includes the trans, etc.
 
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Discussion Starter · #3 ·
Factory heads will have no problem supporting that kind of horsepower. However, if youd like to rev it out into the 8k range, go with a Ferrea valve springs to keep things happy...might want to throw some cams at it too. Porting is not necessary at that power level.

Truth is, you're throwing a fair bit of money at it. Overbuild it once and never look back. That includes the trans, etc.
Perfect, thank you! From what I have read the Shep 2.5 should be a good fit, I will be launching the car some and I do drive it hard everyday, it's my daily. My other question is does anybody have any experience with the ATR version 2 bellhousing, I hate that rattle when shifting from N to D or P to any gear.
 

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If your planning on launching the car the 2.5 is not going to be a good one. Spend the money for the 1k. The gearset in the 2.5 is stock your gonna tear those gears up. Also if your planning on launching your gonna need axles more then likely as well
 

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If your planning on launching the car the 2.5 is not going to be a good one. Spend the money for the 1k. The gearset in the 2.5 is stock your gonna tear those gears up. Also if your planning on launching your gonna need axles more then likely as well
I don't disagree with a more robust trans, but the Shep 2.5 does have (or at least it did for me) an improved 1st gear. Also, at 891 WHP and 816 tiorque, I made hundreds of drags; axles were fine. Mine finally started giving problems for other reasons, but I went with Shep 1k as I went for more power anyway.

Alexd
 

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Discussion Starter · #6 ·
If your planning on launching the car the 2.5 is not going to be a good one. Spend the money for the 1k. The gearset in the 2.5 is stock your gonna tear those gears up. Also if your planning on launching your gonna need axles more then likely as well
I don't disagree with a more robust trans, but the Shep 2.5 does have (or at least it did for me) an improved 1st gear. Also, at 891 WHP and 816 tiorque, I made hundreds of drags; axles were fine. Mine finally started giving problems for other reasons, but I went with Shep 1k as I went for more power anyway.

Alexd
Thanks for the help! As I said before it's my daily driver, was your car comfortable at the 900whp mark? Was it drivable in stop and go traffic? Sorry for the broad question, it's my first GTR and I'm starting to acclimate to the noise that the car makes, what I don't want to do is take away the fun of the car by adding to much power and making it a full blown race car.
 

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First gear is not the only one that fails just saying. If one of the other gears go out it could cause some serious damage. Same thing with the axles but I prefer to not have a issue down the road if I can help it.
As to if the car was drivable at that hp level the answer is yes. Even at 1300+ its easy to drive on the street I could daily my car if I so wanted.
 

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Thanks for the help! As I said before it's my daily driver, was your car comfortable at the 900whp mark? Was it drivable in stop and go traffic? Sorry for the broad question, it's my first GTR and I'm starting to acclimate to the noise that the car makes, what I don't want to do is take away the fun of the car by adding to much power and making it a full blown race car.

Yes, the Alpha 9 set-up is just better than stock, and very comfortable on the street. He can/will speak for himself but I believe Droptopp (like me) was very happy with his previous Alpha 9, and made that point about it.

The Omega 12 that I have, added mid-range besides more power, but I still haven't gotten it "dialed in" right. Here's a street situation that I have now, that I didn't have with the Alpha 9. Let's say I'm in 4th or 5th gear at say 40 MPH (in AUTO mode), and I floor it; the car NOW will react much like the worst things you see with a over-powered rear-wheel drive car (like a Firebird). What happens is that the car shifts down and as it goes into the more powerful lower gears, it breaks loose (with street tires at normal PSI). And unless I want an accident, I have to back off. Now, I can adjust my driving by using MANUAL and keeping below the shift point (I have programming now to allow a auto-shift in MANUAL at peak RPM, rather than going into limp mode) but again, I have to be careful.

So, is the car streetable at 900 to 1500 HP (for other cars)? The answer depends on how you want to drive it; below 4000 RPM; sure, if you avoid the situation I described above.

Alexd
 

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Yes, the Alpha 9 set-up is just better than stock, and very comfortable on the street. He can/will speak for himself but I believe Droptopp (like me) was very happy with his previous Alpha 9, and made that point about it.

The Omega 12 that I have, added mid-range besides more power, but I still haven't gotten it "dialed in" right. Here's a street situation that I have now, that I didn't have with the Alpha 9. Let's say I'm in 4th or 5th gear at say 40 MPH (in AUTO mode), and I floor it; the car NOW will react much like the worst things you see with a over-powered rear-wheel drive car (like a Firebird). What happens is that the car shifts down and as it goes into the more powerful lower gears, it breaks loose (with street tires at normal PSI). And unless I want an accident, I have to back off. Now, I can adjust my driving by using MANUAL and keeping below the shift point (I have programming now to allow a auto-shift in MANUAL at peak RPM, rather than going into limp mode) but again, I have to be careful.

So, is the car streetable at 900 to 1500 HP (for other cars)? The answer depends on how you want to drive it; below 4000 RPM; sure, if you avoid the situation I described above.

Alexd
I would ask my tuner for a tcm tune adjustment and that would address that.
 

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I would ask my tuner for a tcm tune adjustment and that would address that.
Maybe this is a naive question, or several of them...but can tuners do that without a track with TCM tune adjustments? Do they need their dyno, or can good guesses be made without that? Do I need to create some datalogs a certain way beforehand, from which they might use data from?

Perhaps they maximize perfect matches in torque at shifts...?

Alexd
 

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I launched the heck out of a Shep Stage 2 for a full season and a half with 1000hp on E85. Even hot lapping sometimes. If it had 100 launches probably had more like 200 lmao.

Anything under 1K will be stock gears so they will eventually let loose. Just not designed for that type of abuse and need billet gears for longevity.

Problem is whatever you pay for a stage 2.5 will be thrown away when it blows plus the downtime. I’m sure you can tune around it and sacrifice a little power for longer trans life.

@alexdavis had his trans last for years and he frequents the drag strip.

good luck.
 

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Maybe this is a naive question, or several of them...but can tuners do that without a track with TCM tune adjustments? Do they need their dyno, or can good guesses be made without that? Do I need to create some datalogs a certain way beforehand, from which they might use data from?

Perhaps they maximize perfect matches in torque at shifts...?

Alexd
I have many different tcm tunes over the years. Your tuner should be able to make adjustments to the ecm and tcm tune to help with driveability.

My current tcm tune has the shifting from 1 to 2 pushed to 16km/hr to avoid the gear confusion that would always happen at low speeds.
 
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Discussion Starter · #14 ·
I launched the heck out of a Shep Stage 2 for a full season and a half with 1000hp on E85. Even hot lapping sometimes. If it had 100 launches probably had more like 200 lmao.

Anything under 1K will be stock gears so they will eventually let loose. Just not designed for that type of abuse and need billet gears for longevity.

Problem is whatever you pay for a stage 2.5 will be thrown away when it blows plus the downtime. I’m sure you can tune around it and sacrifice a little power for longer trans life.

@alexdavis had his trans last for years and he frequents the drag strip.

good luck.
What is the noise difference between the 2.5 and the 1k? Also, I see alot of you guys have had the Alpha/Omega 9 kit, what injectors did you find to work best?
 
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