HarrisRacing

Correct. Power difference AT 19 PSI AND ON PUMPGAS is definitely not all that great...sure you get 500 rpms and more ultimate power on the dragstrip...but dare I show what happens when you turn both to 25 or 30 psi?

Here you go...I'll compare my 8374 EFR matchbot numbers to the 7670 EFR: Ran the Matchbot numbers on my setup from my dyno this past weekend to reverse engineer the VE values for my engine. I used my 2.75L stroker, 8,000 rpms and assumed a 15% drivetrain loss from my Wheel HP numbers. My engine is ported head, removed squish pads, 8.5:1 CR, SS +.5mm valves, Hypertune V2 manifold, stock intercooler (which works extremely well BTW!), 3" exhaust, BC stroker crank, stock 86mm bores. The VE's that I came up with for my setup are: 3000 - 72 3500 - 72 4000 - 87 4500 - 91 5000 - 99 5500 - 108 6000 - 113 6500 - 113 7000 - 113 7500 - 111 8000 - 111 8500 - 105 (I made up this arbitrary assumed low VE just to show you the differences in turbos. I did NOT run my engine to 8500 yet) First 8374 EFR: Low RPM data here High RPM data here Then 7670 EFR using the same everything including my VE's: Low RPM data here High RPM data here After you digest that, note that I bumped my BOOST numbers to an even 19 psi (nice round pumpgas number) and plotted it in excel. (see the attached theoretical dyno chart converted by reducing matchbot power 15% to reflect WHP ). I also over-laid a match-bot 7670 chart based exactly on my VE's and the same 19 psi boost. So here's what happens: 7670 gets to 10 psi by 3,000 rpms and is at 19 psi by 3,500. From 4,500 the 8374 EFR is also at 19 psi and the two turbos produce nearly exactly the same power since the efficiencies of both compressors are very close and the engine VE's are identical. at 7,000 rpms however, the 7670 is starting to drop out of efficiency at 7,500 the 7670 is unable to hold the full 19 psi without risking overspinning the turbo, but the 8374 is still chugging happily. at 8,000 rpms the 7670 is absolutely on the limit of the overspin threshold and must be limited to 16 psi...and the 8374 is still happy and making 50 more BHP. at 8,500 rpms the 8374 is STILL making more power and is still not maxxed out on airflow. Since my motor can take 9k rpms, and I didn't want to limit it to 7,750 rpms (what I would consider the absolute safe limit of the 7670 EFR on this setup) I choose the 8374. If you want me to run numbers for E70 at higher boost let me know, but that will NOT help the overspin problem. Don't forget you very well have more top end VE than I do since you are on BIGGER CAMS than me !

You guys talking about my car or the camaro? I weighed mine at 3175 lbs (add 190 with me in it) and dyno'd ~460 rwhp on pump gas. Assuming 15% loss, I'd say the numbers are verified with a 529 HP at this boost and displacement on BW Match-bot software. Here is a video of a little fun run with me and my brother in it (add another 185 lbs) - final weight would be around 3570 lbs. I can pull a log of a 3rd or 4th gear street pull for you guys. Still can't get the medium boost actuator to hold over 16-17 psi on top end so I'm moving to the high one shortly to see if it will hold 19-20 psi on pump. Car runs very very well considering. Have not touched Haltech base timing yet. Tires are 255/45/17 redline set at 8,000 for now.

Ok so I drove my car to work this morning. The single turbo lag is totally livable but I could see someone going 7670 if you wanted all out response and wanted to keep revs down. Can't hurt to try other than fitment. The 8374 shares dimensions with the 9180...the 7670 does not. Meaning if you get tired of the 7670 and want to go bigger, you can't make it just a bolt on affair. But honestly. I would like to see what you could get it to do with 7670. It would be insanely responsive.

I honestly don't think it will be as large of a difference as you think. You've got cams which moves your VE up to the top end and VE decides a whole lot about response. I think it's backwards thinking to try to put cams in a motor then put a smaller turbo on. My match bot has what I think are pretty good VE numbers in them. Also the haltech thinks in VE numbers so I'll see what my map looks like today and give you an idea where to start. I will set up a match bot for you.

It would be silly imo to put anything smaller than an 8374 on that engine! You have a touch more lift on the cams but our builds are almost identical. You planning on running ethanol with the higher compression will likely see full boost at 3800 rpms or less even. I have seen 20.1 psi at 4077 rpms trust me it will drive incredibly well! I ran the numbers. Mine are almost spot on so far. Search "matchbot"

No ego here. After pulling down the twins during my rebuild I decided I was going single no matter what. I initally thought to use a smaller single when I was thinking of staying 2.6 and actually inquired about the 7670. Geoff with full race gave great advice on not using the 7670 due to potential to overspin on an rb26 (even on pumpgas) and since I'm stroker it would only complicate the matter. After running the match bot models he's dead right. He was also correct in that the 8374 is an awesome fit for an rb26/28 stroker with basic flow mods. I know I'm just scraping the surface of the turbo now and have plenty left in my tune but I can tell you that drivability is insanely good and top end power is just incredible. I set redline at 8k on mine so far but power is still climbing at that power...so yes the 7670 could probably be fine on a STOCK rb26 if limiting your rpms and dead set on sticking with pump gas. I will run the numbers on match bot for you if you give me some information about your build.

Not much to update. Busy doing other things today. I did, however, take an hour to make a heat shield for the turbine housing. I wanted to protect my powdercoating.

Here is the data for the gear change from 3rd to 4th. Sorry I'm logging ALL channels now so resolution isn't as good as it could be. My brother also short shifted because the tachometer is off a good bit.

Perfect. Thank you!I did get the haltech to start running closed loop boost with pretty great success so far. I didn't realize you can make the closed loop a table just like the open loop. Basically ended up taking my open loop numbers for 17 psi and making them the higher boost table. I didn't play much with it yet but for sure had greater response than before and looks like it will hold more boost up top! But yes that actuator should solve a lot of my problems. Oh and this. https://youtu.be/BVYG2ziS9IM

Very happy so far! https://youtu.be/BVYG2ziS9IM

There is no response issue whatsoever. The single 90mm hypertune is not the issue. The problem is the medium boost cannister for the internal gate on the EFR starts "cracking" open around 9-10 psi...as you adjust it tighter this number goes up slightly, I'm having to keep the port open on the solenoid so long that when it finally comes into boost the boost controller was making it overshoot the target boost at 4500 rpms. If I run JUST wastegate with no boost supply to the cannister it will hit 23 or so at 4100 rpms (this shows what the turbo and engine will do because effectively the gate is held shut. Trust me it's coming on strong, I was tweaking the boost duty cycle in the haltech for it to try to smooth the boost spike (and then resultant FALL) with moderate success - the pull attached is by far the best, but even 2-3% duty cycle changes at rpms were causing drops and spikes. Also on top end the exhaust backpressure is blowing the gate open so I'm dropping boost there too. My duty cycle chart looks silly. Geoff with full race warned me of this already (previously in this thread). I'm going to get the high boost cannister and set it to "crack" at 16-17 just on the wastegate and supply hose (no solenoid spill) then try to get it to hold a solid 20 to redline. When this happens...hello 500 whp and hello 20 psi at 4100 rpms. It's going to be stupid. Between 7-8k rpms the car gained nearly 100 whp going from 12.8 psi to 17. I think I have that last 50 or so whp on pump gas at 19-20 psi. If not, the car may need bigger cams. ALSO I have not TOUCHED the timing. That will help everywhere as well. Also have not TOUCHED the cams. More changes. I'll get a video of a little drive today for you so you can see how it spools and drives. "Responsive" is the word of the day

Heres my data. First tune, ran out of dyno time. Fought boost control for a long time then just went to open loop on Haltech. I should have played with that more before dynoing. Boost on graph is PSI * 10 (for scaling purposes) and is straight from the log. It literally rained while we dyno'd so 100% humidity and 83 deg F ambient. This is STOCK Haltech timing advance (untouched). Only would knock at 20 psi at 4400 rpms during spike. I'm DEFINITELY losing boost response on this because the logs with the wastegate hose pulled are showing 21 psi at 4100 rpms (as opposed to my lazy 4400 that was kinda of spiking at first). Anyway, pumpgas 93 (with the 10% ethanol they have in my area). 2.75L BC stroker New N1 block 86mm bores tomei poncam A 6boost manifold - divided for IWG EFR 8374 EFR .92 IWG divided ported head SS +.5mm valves squish pads removed Hypertune V2 stock intercooler I WILL be ordering the high boost cannister and getting boost leveled out at 16-17 psi for base and using closed loop for tuning. CAR IS AN ABSOLUTE ANIMAL!!! I bet it has 130 mph in it right now! Also it should be noted on STOCK intercooler I'm seeing 115 deg F when hammering through the gears (all the way through 4th) on the highway. It was AT LEAST 125 on the dyno every pull. Air temps drop drastically when on it...ironically they increase while you cruise (or sit in traffic). Makes sense as all that is moving is IDLE air. But under load at 18 psi and this power level the stock intercooler is keeping up well so far. Temps pretty much drop the whole time you are in boost. NICE EFFICIENT TURBO HELPS I AM SURE!!

Heres my data. First tune, ran out of dyno time. Fought boost control for a long time then just went to open loop on Haltech. I should have played with that more before dynoing. Boost on graph is PSI * 10 (for scaling purposes) and is straight from the log. It literally rained while we dyno'd so 100% humidity and 83 deg F ambient. This is STOCK Haltech timing advance (untouched). Only would knock at 20 psi at 4400 rpms during spike. I'm DEFINITELY losing boost response on this because the logs with the wastegate hose pulled are showing 21 psi at 4100 rpms (as opposed to my lazy 4400 that was kinda of spiking at first). Anyway, pumpgas 93 (with the 10% ethanol they have in my area). 2.75L BC stroker New N1 block 86mm bores tomei poncam A 6boost manifold - divided for IWG EFR 8374 EFR .92 IWG divided ported head SS +.5mm valves squish pads removed Hypertune V2 stock intercooler I WILL be ordering the high boost cannister and getting boost leveled out at 16-17 psi for base and using closed loop for tuning. CAR IS AN ABSOLUTE ANIMAL!!! I bet it has 130 mph in it right now! Also it should be noted on STOCK intercooler I'm seeing 115 deg F when hammering through the gears (all the way through 4th) on the highway. It was AT LEAST 125 on the dyno every pull. Air temps drop drastically when on it...ironically they increase while you cruise (or sit in traffic). Makes sense as all that is moving is IDLE air. But under load at 18 psi and this power level the stock intercooler is keeping up well so far. Temps pretty much drop the whole time you are in boost. NICE EFFICIENT TURBO HELPS I AM SURE!!

The red graph one finally had boost flattened out in the dip but knocked a touch in the top. Again no timing changed off of haltech base map yet. 10 psi was 375 whp. Again missing boost threshold

Yeah boost was lazy on the controller. I'm ordering the high boost cannister ASAP. https://youtu.be/9rOq43vEI-c I will get graph from home tonight

Full weight. No jack, spare, floormats, or stereo (but speakers are in doors). AC PS and all still 100% on car. Just got done with tuning session one and went out to enjoy the car. I will need efr high pressure wastegate because I couldn't get stable boost on top end (dropped to 16.5 psi) so I was stuck with only 464 rwhp. But oh my goodness does this car just own all driving it around. What an INCREDIBLE car and incredible powerband. I didn't have time to get timing and all right because I was fighting with boost so much.

I'm going to the dyno today. Hopefully we will have pumpgas charts from 12-20 psi. Every turbo when pushed to 30 psi go to the OFF--ON. You'd need to drive it...it's unreal

Haltech wouldn't controI because it wasn't getting the boost solenoid wiring back to it. just finished running wires from ecu though. Apparently someone cut the wires to install an ebc because the wires to the solenoid did not get signal back to ecu pins. It's all good now though. Made use of one of those MAF wires I wasn't using repinned ecu wire 27 (Front MAF signal) to 25 (Boost control solenoid ground) and then used the MAF 12v switched as a supply for the solenoid...I'm sure it will work now. Going to try to get base duty dialed in for 10 and 12 psi then tweak closed boost mode from there. Based on my tests the other night I should be up in the 18-20 psi range even on medium actuator if the solenoid is up for bleeding the boost. But I'm bringing tools to tighten the arm in case. As fast as this car is at 10 I can't wait for 20! Fyi the EFR solenoid is marked + and - in the plastic. You run 12v to the + and the ecu grounds the - on a pulsed duty cycle to bleed. Closed loop actually starts at your set duty cycle then adjusts to actual boost. Basically I never had it wired up.

And I just though about the boost...probably some nitwit cut those wire in the harness somewhere to install boost control in past. I'm about to go run new ones straight from ecu

Lol... Cross weight is for getting left and right turning the same (use front left and right rear to get %). It's used to jack coil overs to equal cross. to get rear need just find the difference of 100%. 58.4% FRONT 41.6% REAR You guys are funny!

VERY close! 3175 lbs --> 1440 kg 58.4% front 49.7% cross weight.

Going on the racing scales shortly (forgot my buddy has a set)! Any guesses? I'm betting dumping the twins, intake manifold, BOV piping and moving battery has netted me a good loss.

After getting the car done the steering doesn't feel bad at all. Probably not worth changing tbh. I'll save the pulsed output for something more useful (like fans, etc).

Yeah that E85 is tempting me as well. I totally believe the 32 psi by 4200 with anywhere near a decent tune on E85. It's funny how this turbo comes on. It will make the 10 psi on bottom end while cruising and slow spooling, but right around 3800-4k the turbo turns on. I can't wait to get mine to a solid 20 psi on pump. I can NOT imagine what 32 psi on E85 feels like!