How much response do you think one would lose? If autocross and street driving was the primary use with only occasional track or freeway fun runs.

 

Would that even be possible? Sounds like it would end up being right in between the two overall. Which combination do you think would be ideal?

 

How much response do you think one would lose? If autocross and street driving was the primary use with only occasional track or freeway fun runs.

I did find some EFR 8374 videos where I could watch the boost gauge sweep and it does seem to lose some response over the 7670. Its hard to quantify response and I wouldn't know if was a significant difference without driving.

Would that even be possible? Sounds like it would end up being right in between the two overall. Which combination do you think would be ideal?

It is possible to make a hybrid EFR as there are only 2 frame sizes, but I don't know how feasible it is.

One thing I worry about is the compressor backing plate on the 8374 might be bigger diameter so you would have to machine it to fit the 7670 compressor cover- or use the complete 7670 center housing and the 8374 shaft and bearings (though this might not be possible if the parts are not meant to be disassembled/reassembled).

Ideal combo for the rotary? Or ideal combo for the rotary with the 7670 compressor?

IDK, but my hunch is the rotary would like the bigger exhaust wheel to compressor wheel ratio like a stock rotary turbo. EFR7680 in a T3 exhaust housing with small diameter runner manifold is the first 76mm compressor wheel hybrid I would try if I had the choice.

 

BLUE TII

Sad news from my gargage.
I just started stripping down my TII and got to the turbo; the no play but the 7670 shaft takes some effort to spin now.

Turbo probably toast from when the front plate cracked right at the turbo oil feed passage.

After talking to a friend who had a similar experience of cranky turbo I put some Seafoam in the turbo oil feel and let it sit overnight and spun the turbo up while hosing WD40 into the turbo oil feel hose.

It spins better than when it was new (wd40 is thinner than motor oil) and has that tiny bit of shaft play back like when new instead of feeling all bound up.

Hopefully it was just coked up from cooking the little bit of oil that was in it on hot shut down after the engine failure. I guess I will see what is in the turbo oil drain hose when I get that off!

Weird that at no point did it ever feel "gritty".

 

no turbo expert, but when HC blew his turbo in a thread, a few people chimed in about garrett turbos IIRC running fine with huge chunks of the compressor wheel missing, without affecting the turbos' performance.

Not sure if this applies with the EFR's though. And since you stated that yours was just "binding" and not necessarily damaged.

 

Yeah, I remember someone saying the same about running EFR exhaust wheels all messed up just fine on race cars- was it Full Race Geoff?

I guess the double row angular contact bearings can really take a beating with regards to imbalance.

I am hoping my bearings/cage/seals just had that golden sheen of oil varnish slowing the movement up as can happen.

 

just throw it back on the car. and back on the dyno and see if the power has dropped. if the turbo is bad it will be down right?

 

Your turbo bearings are designed to run with a good amount of oil pressure.. I'm not sure if you have any problems at all since you were testing in a static manner.. It may just have been more "dry" or less residual films of lubrication due to sitting around longer.. or doesn't have the new turbo's priming/testing residual oil...

 

Reporting in:

New fuel pump went in (Walbro E85 compatible 460lph), relayed it and it helped enormously. That flat spot was gone and the graph now looks like what you'd expect. Had way more fuel across the board so the whole tune was altered to accommodate the extra juice. The extra fuel made it much happier overall.

Consistently made 265rwkw/410nm on about 16psi, nice and safe tune. Has a bit more in it I think, but for now I'm happy with how it's set up. This particular turbo really needs high boost to make it truly sing, so E85 and higher boost pressures would really let it shine. But for now I'm just going to get used to the power and plan for flex/E85.

The graph gives you a good idea of the instant response and with heaps of power under the curve it's easy to drive and quick as f$%k. Doesn't matter what gear, RPM or throttle position you are in it just goes. The big *** wheel and tyres help keep it planted but it spins 1st, 2nd and 3rd depending on how hard you launch it. You can temper it pretty easily and I'm finding it pretty easy to keep on track.

Like I said initially, my goal was to gain power without losing response. And that's just what the EFR 7670 does. It makes more power faster, builds boost quicker, and makes positive boost pressure instantly. With none of the associated issues with twins like transition dip, can't-decide-which-turbo-to-engage-solenoids, back pressure, heat, complications etc.

There are other things that aren't quantifiable like drivability. In general it drives better; that's a combination of the Adaptronic and the unrestricted nature of the set up. Throttle response is much better, the car feels lively and angry, the exhaust note is meatier and on WOT just plain scary (but still tame sounding on idle). The EFR itself sounds incredible, it has a beautiful whistle and the flutter is addictive. The recirculated BOV is audble but subtle and sounds great. Oh and it spits flames now! It's absolutely brutal when you floor it, very very quick!

I put together a little video of a couple runs and some flames, and a shout out to the sponsors and shops who helped me put it together, they deserve a mentio. Thanks to everyone who's helped answer my questions or given advice, I've learned an absolute tonne about these cars and everything involved. If you guys have questions I'd love to help answer them.

Next stop: more boost/flex fuel and videos of me driving it!

 

Sexy beast and sounds like it drives awesome.

Can't wait for more video!

 

Sorry, couldn't let this one slip lol, that is incorrect. I know it's kind of off on a tangent but oh well.

Gearing modifies the amount of torque you are transmitting to the ground, if engine torque (WTQ rating on the dyno) remains the same at 100MPH in 3rd, 4th, and 5th gear, that means that 3rd gear would still accelerate the car faster than 4th gear, and 4th gear would accelerate faster than 5th gear.

Example: You have a 1.391 third gear, and a 1.000 fourth gear, and a 3.9 rear differential.

(Trans Gear Ratio) x (Rear End Ratio) = Absolute Ratio

1.391 x 3.9 = 5.4249
1.000 x 3.9 = 3.9000

(Absolute Ratio) x (Engine Torque) = Torque at Rear Axle

5.4249 x 300 ft-lb = 1627.47 ft-lb
3.9000 x 300 ft-lb = 1170 ft-lb

So in 3rd gear you are producing 39.1% more torque at the rear axle than you are in 4th gear if the engine makes 300ft-lbs in both gears at the same road speed.

 

I think he could have meant that he has equal power instead of equal torque, then it applies.

 

Very nice video, what boost level was that last dyno at?

 

Arca_ex
Quote:
Originally Posted by BLUE TII View Post
At 100mph at the top of 3rd gear it puts down the same torque at the wheels as 100mph in 4th gear and also the same torque at 100mph in 5th gear.

That means your rate of acceleration is the same at 100mph in 3rd, 4th or 5th gear.

That illustrates how easy it is to drive, your gears don't matter that much.

Sorry, couldn't let this one slip lol, that is incorrect. I know it's kind of off on a tangent but oh well.

Gearing modifies the amount of torque you are transmitting to the ground, if engine torque (WTQ rating on the dyno) remains the same at 100MPH in 3rd, 4th, and 5th gear, that means that 3rd gear would still accelerate the car faster than 4th gear, and 4th gear would accelerate faster than 5th gear.

Example: You have a 1.391 third gear, and a 1.000 fourth gear, and a 3.9 rear differential.

(Trans Gear Ratio) x (Rear End Ratio) = Absolute Ratio

1.391 x 3.9 = 5.4249
1.000 x 3.9 = 3.9000

(Absolute Ratio) x (Engine Torque) = Torque at Rear Axle

5.4249 x 300 ft-lb = 1627.47 ft-lb
3.9000 x 300 ft-lb = 1170 ft-lb

So in 3rd gear you are producing 39.1% more torque at the rear axle than you are in 4th gear if the engine makes 300ft-lbs in both gears at the same road speed.

___________________________
You are incredulous because you are used to the usual rotary torque output.

Here are the #s off the Excel sheet I created and was referring to-

1,387 ft/lb in 3rd @ 7,777rpm
1,477 ft/lb in 4th @ 5,555rpm
1,359 ft/lb in 5th @ 4,444rpm

=SUM(RWHP*5252*rear end ratio*gear ratio)/rpm

You can go ahead and run the #s in your own Excel sheet if you are feeling industrious.

4.1rear
3.483 1st
2.018 2nd
1.391 3rd
1 4th
0.806 5th
24.8" tall tire (for speeds)

 

Love it when the music kicks and and the credits roll in the video, very slick presentation.

 

Any updates on if the 7674 or 7680 is practical?

 

No and I'm not likely to try juggling parts since my 7670 seems fine after all.

 

i just ordered a 7670 with 0.92 IWG.. cant wait to see how much torque it will make on a 13BREW with a cosmo center iron (smaller ports) and 9.4CR rotors! probably going to stick with my 1.4" ID runner manifold too

 

It all depends on how much boost you run.

Boost = torque

 

im sticking to pump gas, so whatever boost i can run and keep it reliable. Actually really like your idea of swapping the comp wheel for a 60-1, probably be a better match for a rotary but with the badass gamma-ti turbine wheel. Did you ever see if its possible?

 

I hope you get good results. I have 9.7 rotors in my build. Probably have to run water injection at anything over 10 psi.

 

I just ordered a 7670 to run on my 9.7:1 turbo also... interested to see what you guys come up with.

I'll be running WI with mine... so hopefully I'll be able to run some moderate boost levels on pump.

 

Actually really like your idea of swapping the comp wheel for a 60-1, probably be a better match for a rotary but with the badass gamma-ti turbine wheel. Did you ever see if its possible?

Nope, I never took anything apart nor measured anything. Anything is possible, its just machining.

My set up was for a race car so I wasn't really worried about low boost pump gas power any more, I maxed out the 76mm 60-1 Hi-Fi and then switched to the 76mm EFR and gained 40hp and 120ftlbs torque.

 

When you think about spool you have to think about what the compressor is capable of flowing before surging.

The higher boost a compressor can provide at a lower flow rate the better it can spool.

Here is the old 60-1 compressor map (in the big T04S compressor housing)


and here is the 7670 compressor map



see how the 7670 compressor has a better surge line (can provide more boost at lower flow).

That is what gives you better spool and more torque in the low rpms.

 

i received mine yesterday.. tookit apart, unfortunately i think it will take a good bit of machiningto get a t3/t4 type compressor to work with it. the shaft diameter is larger and wheel itself is higher. hot side is larger too, i was hoping you could pop a T3/T4 type chra in, but not compatible either. but im not complaining, i just like to be able to tweak stuff haha

what are people doing for the wastegate actuator mount? this one isnt going to work with how we normally clock our turbos. looks like i have to make a custom mount and somehow not interferre with oil drain line

edit; also if anybody is curious, the turbine exducer is 61.5mm, i wasnt able to find that online anywhere