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Recently went single by replacing my limping twins with a new EFR 7670 turbo kit from Turblown. Car is a '93 FD with pump gas, mild street port, and Racing Beat dual-tip exhaust catback. Differences in the two setups at the time of the dynos are listed below:
Would have been nice to compare the two setups using the same Bonez high flow cat. But we had already welded in the new Vibrant cat (swapped the cats using the same midpipe) prior to getting on the dyno.
Dyno results show the EFR 7670 giving up approx. 15% peak HP @ roughly the same modest boost pressures (247 HP vs. 287), with torque for the 7670 being maybe 5% overall less throughout the curve.
NOTE: I was originally planning on boosting the EFR unit to mid-teens to achieve somewhere in the neighborhood of 320-350 HP. But it appears I am limited by the OE medium wastegate cannister or perhaps the new Vibrant cat(?), which would be surprising since we were expecting slightly better overall flow with this cat + 3.5" downpipe + upgraded intercooler.
Anyway, seems like a good comparison for anyone contemplating a swap of the twins with an EFR 7670 turbo. Comparable performance at near-stock levels wout the complexity of the twins/rats nest/underhood temps, etc.
Is there a specific reason you are running only 10.5 psi on the 7670? I was under the impression that turbo is most efficient at 20+ psi and loves when you crank it up. if you want to run 15 or less the 8374 seems to work better?
Sorry if this comes off as second guessing your setup, that is not the intention. The engineer in me is screaming out that this isn't a good comparison at that low of boost pressure.
Last edited by Lavitzlegend; 08-28-17 at 10:50 AM.
Lavitzlegend
Is there a specific reason you are running only 10.5 psi on the 7670?
NOTE: I was originally planning on boosting the EFR unit to mid-teens to achieve somewhere in the neighborhood of 320-350 HP. But it appears I am limited by the OE medium wastegate cannister or perhaps the new Vibrant cat(?)
Lavitzlegend
I was under the impression that turbo is most efficient at 20+ psi and loves when you crank it up. if you want to run 15 or less the 8374 seems to work better?
People choose the 7670 over the 8374 when they want response over power.
The EFR is boost spiking at 3,500rpm and then dropping off. Was that peak boost or the average boost after 3,850rpm on the EFR?
Having driven both how would you compare their characteristics in terms of response?
We need to see the boost curves between the two runs as blue t2 is pointing out.
In my experience if you are using the OE medium actuator on a 7670, with or without a cat you are going to see 8 psi max past 5k rpms. ( no boost controller).
NOTE: I was originally planning on boosting the EFR unit to mid-teens to achieve somewhere in the neighborhood of 320-350 HP. But it appears I am limited by the OE medium wastegate cannister or perhaps the new Vibrant cat(?), which would be surprising since we were expecting slightly better overall flow with this cat + 3.5" downpipe + upgraded intercooler.
In order to reach 13 psi at high rpms with the 7670 and the medium actuator I had to add a lot more preload to the actuator using the nuts on the actuator rod. The boost would tapper off at the higher end so in order to hold a constant 13psi I need to increase the waste gate duty cycle as rpm increased. I have since switched to the turbosmart actuator and have found that it holds boost at a more constant level and needs less compensation over the rpm range.
Even the best dyno fans will struggle to simulate 60kph or35mph of air - thats barely 2nd gear in most setups. And probably not even the whole frontal area of the car. Just sayin'.
Yes we need to see the boost curves of the two and understand how the boost control is working. If you disconnected/plugged the wastegate pressure line, what would happen (I'm not saying you need to actually do this)?
To clarify questions about the boost curve, my tuner in Dallas said the boost was 10 psi, then tailed off to 9 psi. Said he wasn't able to boost any higher (other than the initial boost spike of 11 psi seen on the curve). They adjusted preload on the actuator rod, but still nada. From what I understand following his discussion with Turblown is that I need a Turbosmart actuator to overcome the existing exhaust restrictions. It would have been nice to know this ahead of time. But I think anecdotal stories like this one are still coming in on the EFR IWG units.
The car drives very nicely as-is, though. Transient response of the 7670 is what others have mentioned previously. When cruising at or above 3000 RPMs, any extra throttle request is quite instant. I'll eventually get boost upped to the mid-teens when I go back for a new clutch. But considering the twins that were replaced were actually limping along (about 200-210 comparable HP) due to the primary turbo suffering inefficiency from a previously unknown vacuum leak, performance is very good overall.
Yeah I really think you will be much happier after upping the boost a bit. It really looks like the turbo wants take off based on the boost spike but probably due to exhaust restrictions the pressure is building up enough to push open the waste gate.
Make sure to let us know when you crank this baby up again so we can see the results! I'm looking at putting either the 7670 or 8374 on my 10th AE at some point in the next year or two and still can't decide...
To clarify questions about the boost curve, my tuner in Dallas said the boost was 10 psi, then tailed off to 9 psi. Said he wasn't able to boost any higher (other than the initial boost spike of 11 psi seen on the curve). They adjusted preload on the actuator rod, but still nada. From what I understand following his discussion with Turblown is that I need a Turbosmart actuator to overcome the existing exhaust restrictions. It would have been nice to know this ahead of time. But I think anecdotal stories like this one are still coming in on the EFR IWG units.
The car drives very nicely as-is, though. Transient response of the 7670 is what others have mentioned previously. When cruising at or above 3000 RPMs, any extra throttle request is quite instant. I'll eventually get boost upped to the mid-teens when I go back for a new clutch. But considering the twins that were replaced were actually limping along (about 200-210 comparable HP) due to the primary turbo suffering inefficiency from a previously unknown vacuum leak, performance is very good overall.
Here is the test I did a long time ago that was back to back. ( I have also repeated it with similar results on other cars)
3" exhaust with cat, and without. OEM BW actuator with Adaptronic select controlling the EFR solenoid. 3 turns of preload
Please note peak torque is 22psi without cat, and 19 with cat.
peak rwhp is 15.5 psi without cat, and 13.7 with cat.
Very nice! My setup experienced similar tapering off of the boost; though, not quite as dramatic. Is that why the Turbosmart actuator is offered to help alleviate this issue?
Very nice! My setup experienced similar tapering off of the boost; though, not quite as dramatic. Is that why the Turbosmart actuator is offered to help alleviate this issue?
Correct, as back pressure goes up, its harder to keep the WG closed. Back pressure goes up as boost pressure, and RPMs go up. This is less of an issue with the bigger turbos, as they have bigger turbine wheels = less back pressure( also lower shafts speeds are required from the bigger compressor wheels too).
First time I've seen a half bridge on one of our 7670 iwg kits. 8 psi on pump gas made 348rwhp. They could not get any more out of the medium actuator on the top end. They are upgrading to a Turbosmart.
This one is from DNA garage..They are tuning 4 cast kits today. Another one made 310rwhp at 6 psi on pump(street port)
08-27-17, 10:43 PM
