I decided to take my GT-R to the next level. I am planning to go with a pair of mirror immage Precision or Garrett turbos and run E85 on a flex fuel tune and aim for about 800 rwhp. Probably about 14 psi on the Katech LS3 after I have pistons and rods swapped out from what I am told. I picked a tuner known for making giant power drive very nice. I figure if he can make wicked high horsepower drive nice that making 800 rwhp drive nice with same platform should be easy for him. For the skeptics, there is no good reason to put turbos other than I want to hear a cammed out pushrod V8 with blow-off valve music and enjoy the smell of burnt ethanol!! How much more American can it get than that?!? Im lucky to live where e85 at the pump is plentiful.
Decided to go twin-turbo on my GT-R
- Thread starter anorwitch
- Start date
I can relate and appreciate your desires.
I recently did a change on my Cobra. I had the Ford Racing 427W with a snottier cam that what they came with. It was a beast. Dynoed 469 HP at the tires, but was not fun to drive in traffic or slow.
Well, it leaked coolant into the oil, spun the center cam bearing, sheared the drive pin, retarding the cam so all 8 valves kissed the piston.
Engine got new bigger heads, light hone and new rings and bearings, and much tamer cam and vortec supercharger. Still tuning and have't put the smallest (highest boost) pulley on it yet, but checks all of the boxes. SO MUCH better manners now, and the boost makes up for where the torque would start falling without. Should be around 700 HP all said and done (crank)
Anyways, it was already planned, but I've built basically the same engine (displacement, 220 AFR heads, same cam) but twin turboing for the GT40.
I recently did a change on my Cobra. I had the Ford Racing 427W with a snottier cam that what they came with. It was a beast. Dynoed 469 HP at the tires, but was not fun to drive in traffic or slow.
Well, it leaked coolant into the oil, spun the center cam bearing, sheared the drive pin, retarding the cam so all 8 valves kissed the piston.
Engine got new bigger heads, light hone and new rings and bearings, and much tamer cam and vortec supercharger. Still tuning and have't put the smallest (highest boost) pulley on it yet, but checks all of the boxes. SO MUCH better manners now, and the boost makes up for where the torque would start falling without. Should be around 700 HP all said and done (crank)
Anyways, it was already planned, but I've built basically the same engine (displacement, 220 AFR heads, same cam) but twin turboing for the GT40.
That Cobra sounds fun! I met with the engine builder today and the guys that tune the setup. It looks like we have a game plan. Going to be a 416 cubic inch stroker on all forged internals with Titanium intake valves and inconel exhaust valves with a pair of Precision turbos on a Holley tune. It will be built for perfect manners and bullet proof strength. Should be good to over 1200 rwhp and 8000 rpm and we will set it up to be 800 to 850 rwhp with a rev limiter set to 7000 on a conservative tune with pump E85.
Ron McCall
Supporter
1st, 2nd and 3rd, the back tires are your safety fuse.
You start pushing 700 ft-lbs in 4th and up, you may have problems with the input shaft and geartrain. I was planning on using a tremmec 9080. But back in November, press release said they were going to make a manual transaxle based on the 9080. We'll see how the electronics development comes out.
At least with the 9080, they're becoming cheap and readily available on Ebay.
You start pushing 700 ft-lbs in 4th and up, you may have problems with the input shaft and geartrain. I was planning on using a tremmec 9080. But back in November, press release said they were going to make a manual transaxle based on the 9080. We'll see how the electronics development comes out.
At least with the 9080, they're becoming cheap and readily available on Ebay.
I am on a fresh Ricardo transaxle and I have heard they are good for 1000 rwhp.
I have 3 Vipers - 01 with a 10L stroker and a vortech; 08 heads/cam/intake; 17 acr-e heads/cam/intake.
Of the 3, the 01 is my least favourite because of the blower. Had it just been a built engine it'd be my most favourite.
Going f/i means more weight, more cost, more parts. Less reliability. Harder to work on. More to go wrong. And the power curve just isn't the same as a strong n/a build.
On my 917 I initially toyed with hanging 2 turbos out the back because it would have looked so cool, but 10 years later I'm thankful I didn't.
TLDR - Gimmie a donkey-dick sized heads/cam/stroker n/a combo on a V8/V10/V12 than a blower/turbo.
Of the 3, the 01 is my least favourite because of the blower. Had it just been a built engine it'd be my most favourite.
Going f/i means more weight, more cost, more parts. Less reliability. Harder to work on. More to go wrong. And the power curve just isn't the same as a strong n/a build.
On my 917 I initially toyed with hanging 2 turbos out the back because it would have looked so cool, but 10 years later I'm thankful I didn't.
TLDR - Gimmie a donkey-dick sized heads/cam/stroker n/a combo on a V8/V10/V12 than a blower/turbo.
I must disagree with you on this.
Going from donkey dick cam with warts
to tamer cam plus 5 lbs, the boosted tame came engine is much more pleasant all the way around.
More torque 600 RPM to 3000 RPM due to the cam, then more torque from 4500 RPM up because of the boost. Pretty close to the same in the middle.
One worry I do have with the twin turbo set up is turbo lag then coming unhinged. Hoping the electronic wastegate control can mitigate that.
It is kinda packed like a queer's ass, but parts all come off easily for access to everything. There's a cold air duct molded onto the hood to get cool air to the filter, and a large intercooler in the front.
Going from donkey dick cam with warts
More torque 600 RPM to 3000 RPM due to the cam, then more torque from 4500 RPM up because of the boost. Pretty close to the same in the middle.
One worry I do have with the twin turbo set up is turbo lag then coming unhinged. Hoping the electronic wastegate control can mitigate that.
It is kinda packed like a queer's ass, but parts all come off easily for access to everything. There's a cold air duct molded onto the hood to get cool air to the filter, and a large intercooler in the front.
It almost didn't happen. I am going to use a Tick water to air intercooler sandwiched inside the Holley Low Ram intake manifold. Yesterday I called Tick to order it and found out it was a 6 week lead time. I just don't want to add six more weeks to this project beyond what it would take to finish. I told myself that I would call 3 distributors and if I struck out all 3 then I would go naturally aspirated. Shockingly the second place I called had just one in stock. This is amazing in these days of "Just In Time delivery"/drop shipping. I had similar issue with the turbos. A call to Precision resulted in word that it was going to be 2 weeks to build one of the two turbos as Precision doesn't keep stock on reverse rotation units. Fortunately my engine guy does a lot of R&D for Precision so he called and put some pressure on them. Now my turbos are set to ship Monday.
Atta boy!!!! Im looking forward to finally seeing this beast on the road!
Frank Clark
Supporter
My SLC has been through too many iterations to count. Currently LSX (Actual Iron block LSX) with single GTX4294r. Very happy with this iteration. For this one, I prioritized being able to maintain/work on the car. To that end, log manifolds (previously had proper headers), single turbo at the back (opens up space around motor and reduces under the tail heat). Haven't turned it up past 60% on the boost controller, but at that point it's making 800hp with fuel rich and timing conservative (for E85). Runs great at 650hp on pump gas (has flex fuel setup) at 20%. I do have 2 coolant radiators, 2 coolant pumps, 2 oil coolers, trans cooler, IC Radiator, IC pump and still have battle heat when trying running WOT mile after mile.
Folks say you can't use that much HP in one of these cars. I call BS. While it does not launch like a drag car; with a small wing and decent pavement it will run WOT once in 3rd. Of coarse at that point if you run the tires over some road paint it will break loose.
Folks say you can't use that much HP in one of these cars. I call BS. While it does not launch like a drag car; with a small wing and decent pavement it will run WOT once in 3rd. Of coarse at that point if you run the tires over some road paint it will break loose.
Frank Clark
Supporter
PS, don't use those exhaust flex bits with a turbo, I've since swapped them out for the accordion style.
I'm using a predator engine
Why did you switch to the iron block? Won't aluminum hold that kind of power? 100lb weight penalty, correct?
Step by step. It will be GREAT! I have a fully forged 416 cubic inch motor with some really amazing heads now and all the supporting valvetrain. The engine build, turbo setup and tune is being done by a shop that does R&D for Precision Turbos. My goals are 800 to 850 rwhp on e85 with water to air intercooler inside the the intake manifold. It is being designed with the goal of very very low boost threshold and minimal if any lag at the expense of ultimate horsepower. The fully built 416 engine is to make it bomb proof for reliability. We are going with a 19 inch Hoosier DOT track tire to help make it possible to get it to the ground. We flew from Florida up to the NE and back today with the engine builder and the tuner to visit with the guys building the car. We had a GREAT meeting and everyone is perfectly aligned on the project and all are confident that this is going to be awesome. In the meantime, the builder has modified the body at all four wheel openings to have near zero wheel well gap which is a visual problem with all of the GT-R cars because the body was designed to look good at ride heights that are totally impossible for the street. At 4 inch ground clearance, it had 3 inches of gap. Now at 4 inches of ride height, I have less than 1 inch of wheel well gap! It looks amazing!!! I attached a before and an after of the rear wheel well with wheel. These 2 pictures are at the same ride height / ground clearance. It is a night and day difference
Frank Clark
Supporter
In general an LS iron block is 100lb penalty. The LSX is more than that (thicker walls than a production block).
The 'boost ready' LSX (B15) is pretty darn cheap at about $12k. An aluminum block that will take 6 bolt heads (which you really want) is every bit of $6k on it's own. I did run the engine as delivered (with oil/valve train upgrades) for a while, till I broke a valve. So it was reasonably budget friendly.
I was also looking to cure my reliability issues. I've been through a New from GM LS7, Freshly built LS1, more Toyota V8s that I can keep track of (had 3 blocks, but those accounted for more than 3 roasted motors). The iron blocks are simply more robust.
I use the car for open road racing where weight is not really an issue. But running those high speeds mile after mile can really tear up stuff! Keep in mind there is a big difference in running a 1000hp street car/drag car and running 20+ minutes using most of that HP. I've had engines that where just fine the first 100 miles...
Current iteration has Boost Line rods, custom JE pistons and all the other goodies. In theory it's good for 2000hp, but it will never see that in my hands. As it stands, acceleration is so-so at 190. So eventually I'll probably turn it up for whatever the current turbo is worth.
Motor was on dyno today. 578 hp and 518 tq without the turbos bolted on. Just a quick shakedown and leak check with safe tune. Engine will be pulled and put into the car then turbos get bolted back on. Should not be hard to get to 850 rwhp with conservative tune.
I love the rear wheel gap work. Very aggesive look and really improved the stance.
Adam,
I'm curious what size wheels/tires are you running on your GT-R?
I'm curious what size wheels/tires are you running on your GT-R?