EFR 6258 vs 6758
 

So right now I have the 6258 at 17psi making 311/285. I am very happy with the numbers, but I am reading more and more that the 6758 can make more power, and the loss of spool is marginal. Who's made the upgrade and what have you noticed? What kind of power can the 6758 make on similar boost?

IIRC the outside dimensions are identical so it would just be a straight bolt-on swap.

You need a 7163.

Do it.

For great justice.

I don't want to re-do my manifold and exhaust. I also don't see a need for the kind of power it can produce in such a small car. That's why the 6758 is kind of an idea. Not something I'm guaranteed to do, but if I knew I could sell my 6258 (3000mi) and get a 6758 with marginal difference in cost, I would consider it.

I think soviet is the only one.

Funny how Russians think alike hah

I just went straight for the 6758 after soviets experience.

I went for the S366.

Are you stuck on 17psi for some reason? The 6258 should be able to make more power as you increase boost, if more power is what you are after. It would likely be less expensive than buying a 67 and taking a loss on the 62.

The 7163 is on the same frame as the 6258 and 6758. I believe it is a direct swap turbo. You would want to verify that but I am 95% sure that is the case.

How much more boost can I run with 93 octane and ~8.6-8.8 compression?

All of it.

Pretty sure FM proved that the GT2560r is just as good so why don't you just get one of those?

(I can't tell if I laid the sarcasm on thick enough so I wrote this footer)

Which one does the Trackspeed Engineering kit use? I would use their R&D and follow suit (since we laying on sarcasm).

Funny thing is that listening to people on this site, looking at Soviet's thread, and the mythical TSE turbo kit, I just decided to put together my own package. I love driving this car, it feels incredible. So really, how much boost? My timing according to tuner is still pretty conservative.

How much boost? All of it.
How much timing? All of it.

But seriously, I'm only half joking here. If you're at 17psi, that turbo should handle well into the mid 20's, and if your timing is conservative, you should be able to bump that up another 5* or more depending on load.

The issue then becomes with fueling: you can only go so far on pump gas. Then you need water/meth/etc or run e85 or race gas.

Then you will start running into much more important problems, like replacing grenaded transmission, diff, axles, etc.

I already have an MSM diff with the bigger axles, and it's a puddymod stage 2 cryo treated and with 3.63 mated to an MSM 6-speed via a super miata driveshaft, and fm lvl2 clutch, if that matters.

I get 93 octane, will talk to tuner and see what he thinks.

At over 400whp, all that stuff will be pretty much at or past the limit.

Also something to consider is uncorking more power with more flow. Like a squaretop or honda mani, tb, and maybe even cams.

That's what I'm doing lol. Just picked it up today

I was considering the squaretop or the Honda d or h series manifold. I have 2" intercooler piping but that's plenty large, it's the same size as the cold side exhale port (I forget the name) on the turbo

Weight reduction is another idea. Might want to ditch ac. Anyone know what the compressor and condenser are worth in lbs?

2" ic piping, if I'm not mistaken, should max out near 400hp at full tilt assuming no sudden bends or anything

If E85 is available, that's likely your best bet for safely increasing boost and timing for more power. This would require an upgraded e85 compatible pump, 750-1000cc injectors and obviously some tuning (you may have some of these items already).

This turbo will flow a max of 44lbs/hr which is roughly 440hp. As others have stated, nearing 400hp (and sometimes less than that) the drivetrain is on borrowed time even with a 6-speed and a torsen.

I have to ask, if its a rocket already and your are happy with it, why not just drive it for a while?

Because the only thing better than enough cocaine is more cocaine.

You know what. I think maybe everyone else did all this math for non compressed flow. A car turbo pushing 300cfm at 30 psi (should be closer to 450hp) through 5 feet of 2" ic piping with 4 90° bends is only losing loosing ~0.14 psi to pumping loss. A normal 12psi @ 170cfm 250hp setup is loosing like 0.08psi in the piping. I estimated each 90° bend at r=2d to be equal to an additional foot of pipe for my rough math. Looking at the numbers thats nothing I'd worry about, its still typically being eclipsed by the IC at that point. The fact that my math draws the conclusion that everyone over looked a basic condition kind of makes me want to do it over tomorrow.

Since when did The Forum Collective decide that Torsens and MSM diffs are questionable at 400whp? Are there a bunch of broken diffs that I haven't seen?

IMO, the diff is bombproof. Axles too, as long as it's a street car that doesn't get launched. Tranny needs to go at 400whp, though.

He's got a street car, but has been talking about taking it to the track on sticky tires

I've regularly seen Torsens break on ~400whp/350rwtq street cars, after a single street (ie medium to low grip surface) launch.

My Torsen blew up at the dragstrip, but it took a prepared (sticky) surface and wheel hop to get there. Before that, it survived countless launches at autocrosses, etc. As long as the wheels can spin, it acts as a fuse for driveline components (except for the transmission which, as Sav points out, has a finite torque capacity).

It's a Torsen but not stock. Cryo treated with upgraded hardware inside. It also has a solid sleeve compared to stock.

I wouldn't worry about the rear end at all.

Sticky drag radials would actually help it survive.

Trans is going to be the pucker factor.

Until you dead hook.

That's a good thing. Sidewall flex is safe.

Wheel hop on street tires is bad.

Rubber band vs. jackhammer.

A bias-ply slick will wrinkle and give that extra cushion you want but a drag radial wont have that cushion or at least as much. Dead hook on a radial breaks parts.

I totally get where you're coming from with wheel hop, street tires at the drag strip are the worst lol

You really think a dead hook on a radial is going to be harder on your rear end than a hippity-hip-hip-hop street tire? Come on now. :giggle:

Oh not at all. Wheel hop is the devil. Drag radial is a step up from a street tire for sure. I'm just saying the radial wont give that cushion and that initial shock will still break things. Slicks and skinnies are where its at though.

Drag radial will not dead hook most the time. It will hop, and because it is stickier than most others it will cause way more damage than some dinky all season which will spin like crazy.

A wrinkle wall slick will load up and dead hook, which is what he was getting at.

*edit: +1 what smurf is saying

+1 to running ALLOFIT :skid:

IMO, I'd max out fuel/boost/timing with 93oct on the 62 (or 67 :drool: )

Wouldn't bother with E85 on those pistons.

huh?
why not?

Its not like you NEED high comp for e85.

Well yea.. not saying 'not possible'. Just sounds like OP has more wiggle room with 93oct currently. E85 fuel WOULD be the next thing on the list after 93oct limits are met.

yeah.... good luck getting to MBT on 93oct and >20psi, no matter what your compression ratio is.

I'm fairly certain my 400whp, 93oct, 25psi(?) tune was detonating and I think it was single-digit timing in boost.

For "ultimate glory" I'd do:
- EFR 7163
- E85
- boost by gear
- traction control
- dual-port wastegate and 4 port EBC solenoid so you can run lower psi in first few gears

What tranny? A T10 looks better and better by the minute.

He uses an FD tranny. It's fine.


Oh wait i thought that was Reverant for a minute. My bad. :giggle:

with careful boost by gear and the boost range offered by dual port wastegate I think you can live with a 6 speed on the street.

My 6258 is sounding better with every post haha

Hey psi can I dm you any way?