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I hope it works out. Possibly, the owner is on spyderchat so I wouldn't discuss negotiations too much! It should be a great street car at 8psi. I'd keep the 19psi for known good tanks of E85 and special occasions. Driving on the ragged edge it only takes one small hiccup to go boom. At 8psi you should be able to daily drive for a while. Good luck!
 

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I would go on the K20 engine forum and see if the stock internals can handle 19 psi of boost, even on E85. I doubt it can.
 

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Discussion Starter #43
Thanks guys, If I run it at 8 psi, I think it will hold up. I'll check with the K20 forum and see what they think about higher boost levels on stock internals. I'll be running only E85.
 

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Discussion Starter #44
K20 folks think it will hold up if engine is in good shape, even at high boost levels. Worst case I replace the engine, probably with stronger internals.
 

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I would go on the K20 engine forum and see if the stock internals can handle 19 psi of boost, even on E85. I doubt it can.
I poked around some. Around 28psi on E85 seems to be the max for e85 and stock internals. The issue is excess torque and rod failure. Basically, boost must be limited at lower rpms to keep torque down. The build I saw had an rpm dependent boost curve and purposely did not go past 7psi until after 6000rpm. This was not spool related but rod related. Probably also helps transmission longevity. Doesn't seem very drivable to me. Linear, linear, hit 6000 and bam. Was over 400 ft/lbs and 700hp but not really very usable. This spyder has a similar build, dual 340s, big turbo, 2K injectors, etc. If the intercooler and plumbing are up to it then 19 should be OK as long as it is using an RPM dependent boost curve. Most people seem to want to stay around 8-12. I think set and forget at 8 should have a decent chance of staying together and not overwhelming the chassis.
 

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Discussion Starter #46
That makes sense, for street driving 8 psi should give good power and hopefully keep the engine together. It does have upgraded axles and trans. I'll have to see if I want to change suspension and/or add more braking power.

Oh, I'm attaching dyno sheet - I think yellow + was at 8 psi and green + was at 18. The way car is setup there is just high and low. Runs were using E85.

Does seeing dyno sheet give any further insights to your previous comments?
 

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Spectra Blue 2003 SMT with Quaife LSD
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That makes sense, for street driving 8 psi should give good power and hopefully keep the engine together. It does have upgraded axles and trans. I'll have to see if I want to change suspension and/or add more braking power.

Oh, I'm attaching dyno sheet - I think yellow + was at 8 psi and green + was at 18. The way car is setup there is just high and low. Runs were using E85.

Does seeing dyno sheet give any further insights to your previous comments?
Can’t see the dyno sheet
 

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Discussion Starter #49
I poked around some. Around 28psi on E85 seems to be the max for e85 and stock internals. The issue is excess torque and rod failure. Basically, boost must be limited at lower rpms to keep torque down. The build I saw had an rpm dependent boost curve and purposely did not go past 7psi until after 6000rpm. This was not spool related but rod related. Probably also helps transmission longevity. Doesn't seem very drivable to me. Linear, linear, hit 6000 and bam. Was over 400 ft/lbs and 700hp but not really very usable. This spyder has a similar build, dual 340s, big turbo, 2K injectors, etc. If the intercooler and plumbing are up to it then 19 should be OK as long as it is using an RPM dependent boost curve. Most people seem to want to stay around 8-12. I think set and forget at 8 should have a decent chance of staying together and not overwhelming the chassis.
piston rod or push rod, or both? LOL
 

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Since its an overhead cam, and not overhead valve, it does not have pushrods.
 

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I poked around some. Around 28psi on E85 seems to be the max for e85 and stock internals. The issue is excess torque and rod failure. Basically, boost must be limited at lower rpms to keep torque down. The build I saw had an rpm dependent boost curve and purposely did not go past 7psi until after 6000rpm. This was not spool related but rod related. Probably also helps transmission longevity. Doesn't seem very drivable to me. Linear, linear, hit 6000 and bam. Was over 400 ft/lbs and 700hp but not really very usable. This spyder has a similar build, dual 340s, big turbo, 2K injectors, etc. If the intercooler and plumbing are up to it then 19 should be OK as long as it is using an RPM dependent boost curve. Most people seem to want to stay around 8-12. I think set and forget at 8 should have a decent chance of staying together and not overwhelming the chassis.
The problem with using this turbo and keeping boost down to 8-12 is that you are using a big turbo with lots of inertia and this will mean significant turbo lag. In general, the bigger the turbo, the more lag. If you change to a smaller turbo matched to the power level you can expect at 12 psi, you will have a much more driveable engine.
 

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Discussion Starter #53
Yeah, I'd been thinking a smaller turbo might make more sense. A smaller turbo means a new tune, right?
 

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yes. any changes require a new tune.
 

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Yeah, I'd been thinking a smaller turbo might make more sense. A smaller turbo means a new tune, right?
Spend some time on the K20 engine and Hondata forums and see if you can find a calibration for an engine similar to yours, but with a smaller turbo. Get that turbo, and if you can match injectors and intake manifold, throttle body, and cams; you will be able to use that calibration, at least for a while.

Dave
 

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Discussion Starter #56
The problem with using this turbo and keeping boost down to 8-12 is that you are using a big turbo with lots of inertia and this will mean significant turbo lag. In general, the bigger the turbo, the more lag. If you change to a smaller turbo matched to the power level you can expect at 12 psi, you will have a much more driveable engine.
I'd been thinking the same thing, but if you look at the dyno sheet, is a smaller turbo going to start to spool up a lot sooner than at 3,300 rpm? I don't have enough hand-on experience to know for sure. What do others think?
 

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I'd been thinking the same thing, but if you look at the dyno sheet, is a smaller turbo going to start to spool up a lot sooner than at 3,300 rpm? I don't have enough hand-on experience to know for sure. What do others think?
The smaller turbo will spool up sooner (part of the reason why the engine will be less laggy), but you are supposed to control boost by the wastegate. If your wastegate is not able to do control boost at all speeds, you need a better or bigger WG.
 

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Discussion Starter #58
Yeah I agree with that. I guess I'll change my last question, is a bigger wastegate going to start spool up a lot sooner than at the 3,300 rpm where it starts now? I'm just trying to understand better.
 

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Yeah I agree with that. I guess I'll change my last question, is a bigger wastegate going to start spool up a lot sooner than at the 3,300 rpm where it starts now? I'm just trying to understand better.
Your wastegate is closed when you are spooling up, so a bigger wastegate generally will not make any difference until you hit your boost limit setting. Wastegate too small, you can't effectively control peak boost (especially at high rpm). Wastegate too big and controllability (steadiness of boost control) becomes a challenge.

Dave
 

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Discussion Starter #60
Understood, messing with the wastegate is probably not a good idea. Decision will probably come down to a smaller turbo in a smaller housing or leave things as is and figure out best suspension setup for a certain amount of street driving. Boost has a low setting (8 psi) so car might not be too terribly behaved if I don't get crazy on entrance and exit ramps, lol...
 
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