Originally Posted by Stu @ M Developments

I have this discussion quite a lot with customers looking for different turbos so understand where the fella is confused and understand what he is looking for. The question seems to be - if you already own a 420bhp .63 T34 car and fit a comparable EFR turbo in the hope of setting it also to 420bhp, will the car be faster?

As I'm lying in bed it's hard to show the difference visually without Dyno graphs but think of it this way.
A turbo just makes a small engine into a big one, and it does that with pressurised air, so the faster it delivers the air, the faster you get a bigger engine. At idle, the YB is a 2 litre. A good one, at 15psi is closer to a 4 litre. The faster you can get that 15psi, the quicker you have the 4 litre engine.

The EFR's SPOOL is better, so it will feed the engine with the boost faster than a T series. Also, the engines response time between you changing your foot from power fully off, to power fully on will be greatly reduced with a faster spooling turbo, so regardless of final power being the same, the EFR will deliver it sooner when asked as it can go from zero to say, 40psi faster than any T series.

Secondly, as spool is much improved, your torque band should move left as the engines getting bigger, faster, thus giving you more useable torque area UNDER THE GRAPH. As an example, the T34.63 tends to make peak boost on the Dyno, when floored at 2000rpm, by around 4000rpm. An EFR will deliver the same amount of air by around 3500rpm. This is because the EFR turbo requires less energy to rotate it so it rotates up to the required speed faster. for any engine driven in this lower engine speed area, the car WILL be faster than a comparable T series equipped car driven at the same speed in the same gear. IE: 70mph roll on in 5th gear side by side.

That's why folk are saying ignore drag strips, as that's about top end power and most turbos here will be equal, as BHP is BHP. Once your out of first gear, a drag car never sees low engine speeds or has worries about spool times as it's just wide open throttle and high revs all the way. That is NOT a test of a turbos responsiveness, it's only a test of is ability to flow air with its wastegate opening and open. A road car turbo test is all about what it does with the wastegate shut. Two very different metrics.

Originally Posted by Mark Shead

I have tested a gtx3071 against a 7064 and at 3800rpm the Efr was making 500ftlb and the gtx was 175ftlb. With that diff why would you ever want to fit another gtx turbo. The same goes for the rest of the range I have tested.

Mark

Originally Posted by turbotrev

Totally get that Mark.
What was the gtx making at say 7000 revs compared to the efr? More? Less?
Do you have a graph of each to show?

Cheers Paul

Originally Posted by turbotrev

Sorry I meant torque not hp, at say 7k?
You really not allowed to post graphs?
Well I never knew that

Cheers Paul

Originally Posted by turbotrev

Er ok, I don't get that, bit over my head but thanks anyway lol

So where are all these efr powered cossies?
Anybody using em rather than just sitting them on stands?

Cheers Paul

Originally Posted by turbotrev

I've heard that calculation mentioned before but I'm not gonna lie I don't fully understand it.
If you was to look at the graphs on the car you tested when you went from gtx to efr I understand it's making torque sooner and lower down the revs but higher up say 6-7k what was the difference (if any) at the torque figure there?
(If that makes sense?)

Cheers Paul

Originally Posted by jontysafe

I'm currently having built a new spec engine as follows:

Intelligently ported head, not going mad on exh ports
Bd16+ in, Bd14 exh
Long rods, forged pocketed short Pistons
8.2:1 CR
Possibly solid lifters??
Custom twin scroll manifold
EFR7163 internal gate
Motec M400
1000cc injectors
Boost mapped to road speed

This is coming from a Gt30 set up so will be interesting to see the differences when done
All going in a shonky Westfield!!

Originally Posted by Mark Shead

If they are making the same power at the same rpm they are the same.

Mark

Originally Posted by jontysafe

I'm currently having built a new spec engine as follows:

Intelligently ported head, not going mad on exh ports
Bd16+ in, Bd14 exh
Long rods, forged pocketed short Pistons
8.2:1 CR
Possibly solid lifters??
Custom twin scroll manifold
EFR7163 internal gate
Motec M400
1000cc injectors
Boost mapped to road speed

This is coming from a Gt30 set up so will be interesting to see the differences when done
All going in a shonky Westfield!!

Originally Posted by turbotrev

Sorry I meant torque not hp, at say 7k?
You really not allowed to post graphs?
Well I never knew that

Cheers Paul

Originally Posted by Mark Shead

So are you the type of guy happy to have 10ftlb more at 7k and 330ftlb less at 3.8k.

Mark

Originally Posted by turbotrev

No not all, if that's what's better then its the better turbo.
Just wondered if it's that good low down the revs is it sacrificing it from higher up in the rev range, that's all.
A mate of mine is looking to get this type of conversion done with yourself so I'm looking forward to seeing how his car drives/feels

Cheers Paul

Originally Posted by Jay,

Im sure it will be ok to put some graphs up as a technical discussion is great to see and learn from

Originally Posted by turbotrev

That will be an interesting comparison.
Did you have all that internal engine work running with the gt30 setup as well though?

Cheers Paul

Originally Posted by gjh

That's hell of an improvement with the 7064! Must make it a far quicker car overall over twisty roads?

Originally Posted by Caddyshack

Have you got any long strokes with efr? The 500 bhp spec looks excellent on 7064

Originally Posted by turbotrev

Nice, cheers Mark.
So that given 100lbft more torque 1000 rpm sooner than the gt30.
I notice the gt30 graph has a flatter, more steady curve than the efr one?
Why such a drastic change in the torque curve but not the hp curve? (besides it going up earlier)

Cheers Paul

Originally Posted by turbotrev

Is yours the 468hp one buddy?

Cheers Paul

Originally Posted by Mark Shead

I have tested a gtx3071 against a 7064 and at 3800rpm the Efr was making 500ftlb and the gtx was 175ftlb. With that diff why would you ever want to fit another gtx turbo. The same goes for the rest of the range I have tested.

Mark

Originally Posted by turbotrev

What boost were these on?
The stock engine and the 500hp one?
2bar ish?

Cheers Paul

Originally Posted by turbotrev

Cool thanks.
Is that why the power curves make their peak first off low down in the revs?
I'm guessing the curves decrease as the boost tails off?
Thanks for taking time to answer all these questions by the way!

Cheers Paul