HBP REW Project update: Dyno and Track Stats/Video
08-19-07, 09:04 PM
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HBP REW Project update: Dyno and Track Stats/Video
Chris Ludwig pushes my half-bridge/single REW GSL-SE on a local 8th mile track ...Boost cut in 3rd, ouch!
Best run so far is a 7.27 @ 95mph in the 8th... On only 10psi of boost!
Here's a link to the original build thread
Will post more soon.
Best run so far is a 7.27 @ 95mph in the 8th... On only 10psi of boost!
Here's a link to the original build thread
Will post more soon.
Last edited by ducktape; 08-19-07 at 09:17 PM.
08-19-07, 09:14 PM
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Here's the graph from the tune that netted the 7.27 pass with Ludwig behind the wheel. 388whp @ 10psi average with a little bit of creep. Ignore the huge green 19psi spike... We had two other completely separate MAP sensors monitoring two distinct ports (throttle-body, and mid-manifold) that say that spike never happened. This all took place in 100* ambient temps, with 200* intake temps. All after two hours or so of load-tuning for driveability.
Turning up the boost in the heat netted nearly no gain, as you can see from this 391 @ 14psi graph. There was a miss at high-rpm, so we resolved to disconnect the boost controller for the time being and packed it in. The intercooler becomes suspect...
Bright and early yesterday morning we took it in for another round on the rollers. After failing to knock more time out of the ET's we were anxious to squeeze it a bit more. Chris concentrated on AFRs under high-boost and timing, cleaning us up to into 10.xx ratios throughout the band and giving back a little timing after torque peak. The results were positive; 407whp @ 10psi. This is the number I wanted to see, 400whp+ at wastegate pressure (street-tune).
Plugging in the boost controller satisfied Ludwig's craving with a consistent, repeatable 423whp @ 14psi. We actually have sheets with higher numbers, but I prefer to post this one as it was the latest clean/safe tune with the highest torque value. Suspicion confirmed, the intercooler isn't intercooling. Measured temps between inlet and outlet showed a 5* temperature drop, but still way above ambient. True, no intercooler can produce ambient temps but we both agree there is a lot of room for improvement. The small size, and rather inexpensive construction are likely limiting in other ways as well.
Intercooler aside, I need to address a slight drop in fuel pressure at high-rpm/boost. As far as track-times are concerned, we're going to need some more traction to run any faster in the 8th. I'm checking on suspension modifications, and changes we can make to the existing setup. Ludwig squeezed out a 1.5 60-ft, and I won't be satisfied til I can do the same and he can cut a 1.4. We are limited with stock wheel-wells to our current size slicks, so you'll likely see us at a test and tune in the near future playing with the springs, struts, and sway bars.
Here's a couple videos from the dyno yesterday:
Ripping through 2nd gear a couple of times, setting the boost controller to 14psi
A nice 10psi run in 4th gear from 40 to 130mph
Turning up the boost in the heat netted nearly no gain, as you can see from this 391 @ 14psi graph. There was a miss at high-rpm, so we resolved to disconnect the boost controller for the time being and packed it in. The intercooler becomes suspect...
Bright and early yesterday morning we took it in for another round on the rollers. After failing to knock more time out of the ET's we were anxious to squeeze it a bit more. Chris concentrated on AFRs under high-boost and timing, cleaning us up to into 10.xx ratios throughout the band and giving back a little timing after torque peak. The results were positive; 407whp @ 10psi. This is the number I wanted to see, 400whp+ at wastegate pressure (street-tune).
Plugging in the boost controller satisfied Ludwig's craving with a consistent, repeatable 423whp @ 14psi. We actually have sheets with higher numbers, but I prefer to post this one as it was the latest clean/safe tune with the highest torque value. Suspicion confirmed, the intercooler isn't intercooling. Measured temps between inlet and outlet showed a 5* temperature drop, but still way above ambient. True, no intercooler can produce ambient temps but we both agree there is a lot of room for improvement. The small size, and rather inexpensive construction are likely limiting in other ways as well.
Intercooler aside, I need to address a slight drop in fuel pressure at high-rpm/boost. As far as track-times are concerned, we're going to need some more traction to run any faster in the 8th. I'm checking on suspension modifications, and changes we can make to the existing setup. Ludwig squeezed out a 1.5 60-ft, and I won't be satisfied til I can do the same and he can cut a 1.4. We are limited with stock wheel-wells to our current size slicks, so you'll likely see us at a test and tune in the near future playing with the springs, struts, and sway bars.
Here's a couple videos from the dyno yesterday:
Ripping through 2nd gear a couple of times, setting the boost controller to 14psi
A nice 10psi run in 4th gear from 40 to 130mph
08-19-07, 09:16 PM
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08-20-07, 11:33 AM
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Nice car bluegrass.
I built a very similar car and dynoed last week. I have to address the same issues you are. I ought to send you some pics of my engine bay. I fit a large NPR intercooler in front and kept all the AC stuff in it. Believe it or not the NPR is a very ifficient core and for the money you can't beat it. The ebay intercoolers are the best if you want no pressure drop but it you want cooling efficiency you need a quality intercooler core. You will have more pressure drop from one side to another but it will exchange the heat! About 2 years ago I had a boy bring me 3 of the large NPR's and I give him 60 bucks each for them. I kept 1 and sold the other 2.
You did a great job on the build up. I'd like to see the boost come up on it and watch the powerband grow
.
I built a very similar car and dynoed last week. I have to address the same issues you are. I ought to send you some pics of my engine bay. I fit a large NPR intercooler in front and kept all the AC stuff in it. Believe it or not the NPR is a very ifficient core and for the money you can't beat it. The ebay intercoolers are the best if you want no pressure drop but it you want cooling efficiency you need a quality intercooler core. You will have more pressure drop from one side to another but it will exchange the heat! About 2 years ago I had a boy bring me 3 of the large NPR's and I give him 60 bucks each for them. I kept 1 and sold the other 2.
You did a great job on the build up. I'd like to see the boost come up on it and watch the powerband grow
.
08-25-07, 03:13 AM
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A couple hours in the garage adjusting the suspension netted a little over a tenth of a second improvement in best time for this car. We'll be into the 6s soon.
This run was again on only 10psi, with 95* ambient air temps.
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08-26-07, 10:44 AM
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That is a quick car for 10 psi! Low 11 high 10 1/4 ETs is very respectable. Just wait till you turn it up!
My FB with the same set up besides the bridge port, it is so fun to drive... I have kept the boost at 20-22 psi since I got if off the dyno. It is blistering fast. I always told people that the best RX7 is a first generation, with a built FD engine, T2 trans and a good solid rear axle. Plus its not too hard on the pocketbook when you buy a roller for 150 bucks or less!
Bryan@BNR
My FB with the same set up besides the bridge port, it is so fun to drive... I have kept the boost at 20-22 psi since I got if off the dyno. It is blistering fast. I always told people that the best RX7 is a first generation, with a built FD engine, T2 trans and a good solid rear axle. Plus its not too hard on the pocketbook when you buy a roller for 150 bucks or less!
Bryan@BNR
08-26-07, 05:24 PM
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Absolutely Awesome! And I'm getting all googly over a couple of hp gain on my na setup..............it would seem my car is just a snot drip in the salty sea of rotary goodness.
Ohhhhh I have so much to look forward to
Ohhhhh I have so much to look forward to
08-29-07, 12:04 AM
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08-29-07, 12:26 AM
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It's a pig. Heaviest year/model plus all the safety gear and my own change to steel bumpers over the stock fibreglass. There are probably lighter FCs running around.
The last time I weighed the car, it tipped the scales at 2420lbs with a 1/2 tank of gas (no driver). Since then, I've swapped to an REW and larger turbo, replaced the stock diff with an 8.8, added a 6-point roll bar, scattershield, and driveshaft loop. If I had to guess, I'd sat it's curbing around 2800lbs+ with me behind the wheel.
The last time I weighed the car, it tipped the scales at 2420lbs with a 1/2 tank of gas (no driver). Since then, I've swapped to an REW and larger turbo, replaced the stock diff with an 8.8, added a 6-point roll bar, scattershield, and driveshaft loop. If I had to guess, I'd sat it's curbing around 2800lbs+ with me behind the wheel.
08-29-07, 12:53 PM
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Hey Ducktape.
Have you had any experience with the factory rear end with upgraded components? Is it even worth my time putting moser's and Racing beat chunk?
If you want a better intercooler, I would look into a liquid/air intercooler with a reservior. you can pump the water through an ice box to get your temps below ambient.
Have you had any experience with the factory rear end with upgraded components? Is it even worth my time putting moser's and Racing beat chunk?
If you want a better intercooler, I would look into a liquid/air intercooler with a reservior. you can pump the water through an ice box to get your temps below ambient.
08-29-07, 01:59 PM
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Hey Ducktape.
Have you had any experience with the factory rear end with upgraded components? Is it even worth my time putting moser's and Racing beat chunk?
If you want a better intercooler, I would look into a liquid/air intercooler with a reservior. you can pump the water through an ice box to get your temps below ambient.
Have you had any experience with the factory rear end with upgraded components? Is it even worth my time putting moser's and Racing beat chunk?
If you want a better intercooler, I would look into a liquid/air intercooler with a reservior. you can pump the water through an ice box to get your temps below ambient.
With the current setup, I'm doing 8000rpm clutch dumps on 8.5 inch slicks building 6psi of boost off the line. I drive the car to and from the events, and when it's time to leave I simply change back to my street tires and drive it home. I don't think I could have that kind of confidence in a modified stocker.
That said, If I was tasked with building a bulletproof FB rear-end I would start with 5-letter diff, replace all the bearings, have the ring and pinion cryo'ed, buy a spool to replace the LSD, and use stainless steel axles.
If you do try it, let me know how it works out. Having an 8.8 all but excludes me from running NHRA street classes, and I'm not fast enough to run in modified. I would love to have a built spec rear-end that would put this car with the other street cars where it belongs.
08-29-07, 02:39 PM
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I never tried upgrading the stock rear-end, but I have my doubts about it being able to hold up to the stress. The first weak spot I encountered with the stocker was the limited slip unit. I blew-up two of them, one on the track on drag radials. I've found they do alright as long as you don't put sticky tires on the car. My eventual solution was to weld up an open diff for the track. It worked fine and never broke, but that was 2 years ago with 100 less hp and never on slicks. The best ET I managed to squeeze out was an 8.1 @ 88mph. If I had to guess, I would say the next failure point would be ring-gear or axles.
With the current setup, I'm doing 8000rpm clutch dumps on 8.5 inch slicks building 6psi of boost off the line. I drive the car to and from the events, and when it's time to leave I simply change back to my street tires and drive it home. I don't think I could have that kind of confidence in a modified stocker.
That said, If I was tasked with building a bulletproof FB rear-end I would start with 5-letter diff, replace all the bearings, have the ring and pinion cryo'ed, buy a spool to replace the LSD, and use stainless steel axles.
If you do try it, let me know how it works out. Having an 8.8 all but excludes me from running NHRA street classes, and I'm not fast enough to run in modified. I would love to have a built spec rear-end that would put this car with the other street cars where it belongs.
With the current setup, I'm doing 8000rpm clutch dumps on 8.5 inch slicks building 6psi of boost off the line. I drive the car to and from the events, and when it's time to leave I simply change back to my street tires and drive it home. I don't think I could have that kind of confidence in a modified stocker.
That said, If I was tasked with building a bulletproof FB rear-end I would start with 5-letter diff, replace all the bearings, have the ring and pinion cryo'ed, buy a spool to replace the LSD, and use stainless steel axles.
If you do try it, let me know how it works out. Having an 8.8 all but excludes me from running NHRA street classes, and I'm not fast enough to run in modified. I would love to have a built spec rear-end that would put this car with the other street cars where it belongs.
I have a entire Mazdacomp stock rearend that I'll be selling. Those are supposed to be pretty stout and legal for NHRA.
I'll be removing it all from my car this weekend, so.......
09-02-07, 10:13 AM
#23
Duck's been on vacation in Florida this week. I think he's miserable because he can't play with the car. He's IM'd me several times talking about how he just wants to come home and wrench on the car.
This week we're going to pull the Ebay IC and recore it with a Garrett core. We know it's not cooling and we're guessing it's a large flow restriction as well. Wanted to do some more dyno work and record pressure drop across the Ebay core but now we're just going to can it. Bryan, I have tried to talk Duck into the water-air IC. He still holds out illusions of this being a daily driver (despite my prodding to the contrary) and the complexities of a water-air system for the street just doesn't appeal to him I think.
The methanol kit should go on this week as well. We're looking to run a 50/50 blend over 1 bar. Ultimately we're looking to run 20 psi on the current turbo. I'm not expecting any huge gains right now at low boost but the benefits will show up down the road.
We're also going to look at how we're going to fit wider tires under it. We're currently running on an outdated 8.5" MT ET Drag. They hooked OK the first night we went out but since we now have the two-step working the car is building about 6psi on the line and we're getting noticeable wheel spin. The one run we tried to run 14 psi netted nothing as the first 100ft was all wheel spin. On 10 psi the 60's are consistently in the low 1.5 range but 1.4s are realistic with some bigger tires and some suspension tuning. That alone should get us to the first goal of running 6.99 on the 10psi spring.
Hopefully by this time next week we'll have all of the above done as well as another dyno session to freshen up the 1 bar tune (assuming we'll gain flow from the new IC core) and some better times to show for it.
This week we're going to pull the Ebay IC and recore it with a Garrett core. We know it's not cooling and we're guessing it's a large flow restriction as well. Wanted to do some more dyno work and record pressure drop across the Ebay core but now we're just going to can it. Bryan, I have tried to talk Duck into the water-air IC. He still holds out illusions of this being a daily driver (despite my prodding to the contrary) and the complexities of a water-air system for the street just doesn't appeal to him I think.
The methanol kit should go on this week as well. We're looking to run a 50/50 blend over 1 bar. Ultimately we're looking to run 20 psi on the current turbo. I'm not expecting any huge gains right now at low boost but the benefits will show up down the road.
We're also going to look at how we're going to fit wider tires under it. We're currently running on an outdated 8.5" MT ET Drag. They hooked OK the first night we went out but since we now have the two-step working the car is building about 6psi on the line and we're getting noticeable wheel spin. The one run we tried to run 14 psi netted nothing as the first 100ft was all wheel spin. On 10 psi the 60's are consistently in the low 1.5 range but 1.4s are realistic with some bigger tires and some suspension tuning. That alone should get us to the first goal of running 6.99 on the 10psi spring.
Hopefully by this time next week we'll have all of the above done as well as another dyno session to freshen up the 1 bar tune (assuming we'll gain flow from the new IC core) and some better times to show for it.
09-03-07, 11:58 AM
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Hey Ludwig.
I have a garret core rated for 650 HP. I was initially going to put it in my 1g but decided the NPR was just too darn easy. So if you guys need it let me know! I started putting end tanks on it to install in my grand national, but I am selling it.
Bryan@BNR
I have a garret core rated for 650 HP. I was initially going to put it in my 1g but decided the NPR was just too darn easy
. So if you guys need it let me know! I started putting end tanks on it to install in my grand national, but I am selling it. Bryan@BNR
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