Monkman33

iTrader: (28)

At this time, i have not actually started an engine with either. Still assembling everything. Perhaps someone else can chime in with more experience?

I like the lower and more set back look. So if there was no major performance difference, i would still go with the Turblown with IWG. Very simple to plumb and more room elsewhere in the engine bay.

lOOkatme

iTrader: (19)

This would be the way I would go. either EFR7670 or EFR8374, get the IWG with shorty manifold.

This has the most direct path to the turbo, no wastegate plumbing to disrupt flow, you don't need a BOV....this is such a good option. Oh, and no open dump wastegate noise, or plumbing back into exhaust.

This is a win, win, win, win, win....too many to type situation.

Haraise

I'd love the 7670 IWG, but they said it'll boost creep with a 3.5 or 4" exhaust. That's really bothering me. :/

Monkman33

iTrader: (28)

Maybe there is a way to have adjustable backpressure in the exhaust? I know restrictor plates were being used to keep boost levels safe for stock ecus.

rx7srbad

simple solution...don't go 3.5 or 4"; 7670 is a small turbo so it will flow just as well with a 3" system.

or add a good electronic boost controller to constantly regulate the boost.

BLUE TII

iTrader: (9)

Wow, you're really not making the choice easy for BNR Stage 3 in sequential vs 7670! Have a dyno at 91?

I do but they are on the shops dyno computer as I never bothered to print out the unimpressive low boost peak #s. It wasn't until I had driven around with those unimpressive low boost #s that I realized "holy crap this thing is fast".

Power under the curve is pretty sneaky.

rx7srbad
Quote:
simple solution...don't go 3.5 or 4"; 7670 is a small turbo so it will flow just as well with a 3" system.

or add a good electronic boost controller to constantly regulate the boost.


Monkman33
Quote:
Maybe there is a way to have adjustable backpressure in the exhaust? I know restrictor plates were being used to keep boost levels safe for stock ecus.

Haraise I'd love the 7670 IWG, but they said it'll boost creep with a 3.5 or 4" exhaust. That's really bothering me. :/

--------------------------------------------------

Boost controller cannot lower boost creep, it can only raise boost.

We FD owners get confused on this because with the sequential twins you can use boost controllers to regulate boost lower by opening the WG door and the Prespool door which acts as an additional wastegate for the primary turbo.

I went through this boost creep issue with my BNR Stage 4 with 3.5" turbo back exhaust. I finally ended up with 60mm external WG and had to port the manifold/exhaust housing huge with flow favoring the WG to solve the boost creep.

I could just run the restrictive RB 3" exhaust I had and have no boost creep problems, but the RB 3" really killed low rpm power/spool.

That is why I absolutely didn't want boost creep on my 7670 and opted for well placed dual 44mm external WGs. Well, it was overkill as I found I could hold 6psi boost (never tried a softer spring to see if I could hold less).

My experience is to definitely run the 3.5"-4" exhaust if you want the great low end power/spool and then if it does creep put a restrictor at the last gasket in the exhaust sytem. The further from the turbo the better as it will not affect spool, but will limit peak exhaust flow.

You can get fancy and put in a throttle plate that closes with boost over your target boost, but it isn't necessary. The 2" restrictor will not affect low end power/spool.

You can also use one of those exhaust tip silencers as the restrictor- I did that for years.

silverTRD

iTrader: (36)

So putting a restrictor behind the mp in front of the exhaust doesn't hurt power or spool? I understand there are variables but overall it's a few to say it won't rob power etc?

Haraise

BLUE TII, awesome post again, thank you.

Have you seen a dyno of an EFR creeping on 3.5 or 4" exhaust? I'm kind of debating, since often creep happens after peak torque and just flattens out the high RPM torque curve. If it's not increasing maximum brake torque, creep can be a good thing (more power possible when the car is in a position to get more safely).

BLUE TII

iTrader: (9)

silverTRD
So putting a restrictor behind the mp in front of the exhaust doesn't hurt power or spool? I understand there are variables but overall it's a few to say it won't rob power etc?

Of course you will make more peak power creeping to 20psi then you will make if you are steady 14psi and the restrictor.

If you mean will the restrictor on a 3.5" exhaust to stop boost creep hurt peak power compared to a 3" exhaust where it had no creep-

then no my findings are the restrictor will not hurt peak power and gain power under the curve.

You size the restrictor to the maximum size that will still keep boost creep at bay by limiting total exhaust flow.

Total exhaust flow is total exhaust flow whether it is straining through a 1.5" hole at the end of the muffler tip in a 3.5" system or going through a whole RB 3" turbo back.

I did not find that the restrictor affected spool at all. That is you still get all the quicker spool/more low end power of the larger diameter exhaust.

I would try to put the restrictor as far back on the exhaust as possible.

BLUE TII

iTrader: (9)

Haraise
Have you seen a dyno of an EFR creeping on 3.5 or 4" exhaust? I'm kind of debating, since often creep happens after peak torque and just flattens out the high RPM torque curve. If it's not increasing maximum brake torque, creep can be a good thing (more power possible when the car is in a position to get more safely).

I have not seen an EFR chart with boost creep yet.

Monkman33

iTrader: (28)

Haraise

Yeah, if the 7670 can do 400whp on pump 91, that's good game for me. Wow.

BLUE TII

iTrader: (9)

IWG EFR 7670 on 3" exhaust/v-mount and with no boost creep.

Very nice.

17psi boost falling off to 14.7psi

That is more than I like to do on pump gas, but I am pretty sure I am getting 87 octane around here when I buy 91 octane.

The power

Well, every dyno reads differently.

Monkman33

iTrader: (28)

Still:
288 ft/lbs @ 3000 rpm
365 ft/lbs @ 3500 rpm
376 ft/lbs @ 4000 rpm
386 ft/lbs @ 4500 rpm
386 ft/lbs @ 5000 rpm
324 ft/lbs @ 5500 rpm

I bet the earlier numbers would have been slightly higher if the run started earlier.

EDIT - added for comparison to the HP curve. Yes, some dynos read higher and lower.

Haraise

Yeah, if the run actually started ~400 rpms before full boost, that's seriously impressive.

Marf

The dyno chart above is Julian's car from FDUK. I believe its 400 fly, not wheel. Oh and its not a ported engine.

http://i157.photobucket.com/albums/t...psei6frsr3.jpg

http://i157.photobucket.com/albums/t...pskwpdzpyc.jpg

http://www.fduk.org/forum/showthread.php?t=32288

We get 99RON over here, no idea what that is in US Octane.

Whatever the real power figure, the torque spread is impressive, very tempted

billyboy

DD are wheel. Barometric, low temps and humidity, shootout, all for the positive side of the ledger - and a generally more conservative dyno.

Enigmatic

I saw that, I'm not too worry about the numbers but that curve is what is so impressive. It bodes well for me and I'm excited - should have results soon I just had a few teething problems post conversion. I am looking forward to see results similar, but I have a street port, a 3.5" exhaust, twin external gates with the 1.05 rear housing, Greddy VMIC and run 98RON, so it will be interesting to see how that changes things.

BLUE TII

iTrader: (9)

Whatever the real power figure, the torque spread is impressive, very tempted

Exactly, we can see the shape of his HP/TQ curves is very similar to my graphs- as in, great torque spread.

I have no reason to doubt his dyno #s and I have no reason to doubt my dyno #s.

Marf

I'm asking Julian if they are wheel or fly figures, like I say I'm sure they are fly. In the UK we generally don't tend to use WHP figures.

Either way, with that response it doesnt really matter, its a damned fast car and is tempting me to spunk a few grand going single

edit: tuner confirms those are flywheel figures, top left of the HP scale - S_HP - estimated flywheel figure

BLUE TII

iTrader: (9)

From what I have read-

A Dyno Dynamics normally shows only wheel horsepower (what it measures).

In Shootout Mode however,
you have the choice of showing wheel horsepower (as measured with set ramp rates/correction factors) or flywheel horsepower (measured whp with an additional +16% across the board).

The chart will show "HP" at the top left if wheel horsepower and "S_HP" at the top left if flywheel horsepower (likewise for "S_FTLB" and "FTLB" torque).

So, if the above is correct; converted back to whp we would have-

334rwhp with boost dropped to 15psi (still Dyno Dynamics HP).

My experience is 330rwhp Dyno Dynamics has been 380rwhp Dyno Jet and 380rwhp Dyna Pack on my car- whatever that is worth.



Another data point is Elliot says he has done 440rwhp @ 22psi on an Airwerks 7670 (non EFR).

If we look at my boost drop the DynoJet 420rwhp peak hp was with boost dropped to 20 or 21psi as well.

So, at the end of all that... the EFR 7670 still looks like a great turbo for 300-400rwhp on a 2 rotor with great response/torque.

Marf

Amen. The 7670 seems like the perfect replacement for someone who enjoys the response of stock twins but wants more powaaaa!

What I'd really like to know is just how low can you get the boost on the IWG 0.92 a/r with a well silenced 3" exhaust system.

Haraise

Is that really a fair statement if that power has to come by way of race gas? Just not very clear what's possible on 91 or 93 pump.

Marf

Race gas?

We get 99RON out of the pump here

http://events.imeche.org/docs/defaul...3.pdf?sfvrsn=2

I know your octane rating system is different to ours, so I've no idea what 91/93 US octane converts to in RON.

Turblown

iTrader: (12)

I believe 98 or 99 ron is our 93 stateside. I thought those figures seemed high for rwhp, but I forgot to ask. I have never displayed a dyno in BHP.