• Got the Contributing Memberships stuff finally worked out and made up a thread as a sort of "How-To" to help people figure out how to participate. So if you need help figuring it out, here's the thread you need to take a look at -> http://www.corvetteflorida.com/forums/showthread.php?t=3581 Thank you, everyone! Rich Z.

427 engine (part 2) - RHS block

Watching your last video several times I noticed that the noise you have is apparently when the car is cold. The other thing that struck me was that in each instance I heard the noise you were turning left. The first time was after you backed out of the garage and went down your driveway. The second time was when the car stalled. I was wondering if you can remember if you had the steering wheel cranked all the way to the left. If so that brings to mind a couple of things. One the noise is the pressure being relieved in the power steering pump. Two since it is cold it is thicker than normal and is not being relieved quickly enough. Which could cause the belt to slip until you straighten the wheels.

As to it happening when you come up on the clutch. Could you be coming up on the clutch and instinctively turning the wheel.

Just something for you to think about.
 
Rich Z said:
Hmm, I'm looking at the log and I'm only seeing 125 kPa right before traction control stepped in. :shrug01:
Click to expand...
YEOW! That works out to about 18 pounds of boost by my calculations!
To convert kilopascals to pounds per square inch(KPA to PSI), multiply the kpa value by .14503773773020923.
No wonder traction control is kicking in..........
Are you sure your wastegates are functioning properly?
If there's THAT much boost, no wonder the airbridge is popping off!
Andy :wavey:
 
CorvetteJohn said:
Watching your last video several times I noticed that the noise you have is apparently when the car is cold. The other thing that struck me was that in each instance I heard the noise you were turning left. The first time was after you backed out of the garage and went down your driveway. The second time was when the car stalled. I was wondering if you can remember if you had the steering wheel cranked all the way to the left. If so that brings to mind a couple of things. One the noise is the pressure being relieved in the power steering pump. Two since it is cold it is thicker than normal and is not being relieved quickly enough. Which could cause the belt to slip until you straighten the wheels.

As to it happening when you come up on the clutch. Could you be coming up on the clutch and instinctively turning the wheel.

Just something for you to think about.
Click to expand...

Yeah, could be. I'll have to play closer attention to what I am doing with the steering wheel when I hear that noise. And there is no law against more than one thing making a similar noise, I suppose.
 
navy2kcoupe said:
YEOW! That works out to about 18 pounds of boost by my calculations!
To convert kilopascals to pounds per square inch(KPA to PSI), multiply the kpa value by .14503773773020923.
No wonder traction control is kicking in..........
Are you sure your wastegates are functioning properly?
If there's THAT much boost, no wonder the airbridge is popping off!
Andy :wavey:
Click to expand...

Well, there are suppose to be 10 lb springs in each of the two wastegates. I opened them up and checked the color coding myself. The vacuum lines appear to be hooked up to them running from the intake manifold. I put them back on myself when I put the exhaust back on recently. That's when I found that one of the connections was loose. And I used the inspection cam to check to make sure that the vacuum hose was still on the back of the intake manifold.

I guess I need to put a camcorder in position to monitor the boost gauge sometime. I really don't like taking my eyes off of the road at all when I'm bearing down on the gas pedal.

Interestingly enough, I am looking at a data page in EFILive that shows the values for each PID selected. It stores MIN, AVG, and MAX values. There are two PIDs for manifold pressure, it seems, that are registering PSI. But the values for MAX don't make sense. SAE.MAP shows a MAX of 22.5 psi, and GM.MAPBOOST_DMA shows a MAX of 22.60 psi.

I doubt this is a measure of actual BOOST conditions coming from the turbos, but I'm asking Mike Carnahan about what those values actually mean.

Bryan at LME told me the engine could handle 25 psi of boost easily, but I don't believe the STS turbos can deliver that much airflow to a 427 cid engine. Aaron Scott did have bigger turbo housings put on the turbos, but even so, they are not really very big at all compared to others I have seen.

Certainly the AFR ratio didn't act like it was going way lean because a lot more air than expected was being pumped into the engine. AFR was running around 11:45:1 at the time of boost, which is actually pretty safe and not at all lean.
 
Well, I got a reply back from Mike Carnahan telling me how much boost was being produced, according to the log file:

On 1/27/2013 8:15 AM, Mike Carnahan wrote:
> 3.62 psi of boost
> Step on the gas Rich :)
Click to expand...

Mike apparently thinks I am still babying the car too much. :D

Besides, if it will break the tires loose like it did at 3.62 lbs of boost, what good will it do continuing to push the gas pedal to generate 10 lbs of boost? :hehehe:

Yesterday I got in the T-bolt clamps I ordered, but still waiting on some different diameters of tubing I ordered to tackle the airbridge couplers.
 
I think you're going to need to get some stickier tires....at the cost of they wear out quicker. But you can't have it both ways. I had Maxxis tires on my CTS V when I first got it. They gripped very well (.96 g's)but only lasted 15K miles. I put Nexxen's on after that but they start squealing at .70 g's, but I have almost 20K miles on them now. Probably have another 5-10K left on them. And I really don't drive them hard, at least not all the time. :D

But with upwards of 800HP you may need racing slicks....:reddevil:
 
85vette said:
I think you're going to need to get some stickier tires....at the cost of they wear out quicker. But you can't have it both ways. I had Maxxis tires on my CTS V when I first got it. They gripped very well (.96 g's)but only lasted 15K miles. I put Nexxen's on after that but they start squealing at .70 g's, but I have almost 20K miles on them now. Probably have another 5-10K left on them. And I really don't drive them hard, at least not all the time. :D

But with upwards of 800HP you may need racing slicks....:reddevil:
Click to expand...

Hah! I tried racing slicks on my GTO way back when, and let me tell you, the term "slick" is well deserved when the roads get wet. I wound up going sideways down a road when it started to rain.

Besides, I think I would rather have the rear tires as the "fuse" in the drivetrain instead of something else that would be expensive to fix.

But all in all, the tires on the car now were supposed to just be a stop gap fix anyway. When Aaron Scott had my car he was constantly complaining about the tires not griping on the dyno drum and wanted me to buy a set of tires from him. Instead I found a passable set of tires and wheels from a guy on this forum, and got them instead. Of course, when I told Aaron I had them, then suddenly it wasn't that big of an issue to him. Quite honestly, from what I have had to fix on the car, I don't see how the car could have even reached power levels for that to be an issue on the dyno anyway. The incorrect throttle body alone (gold bladed LS7 style) would have triggered REDUCED ENGINE POWER conditions. But anyway, I didn't put the tires and wheels on the car till I got it back home. The tires wouldn't be my first choice to buy anyway, but they are better than the age hardened Michelin's that were on the car.
 
Got a new tune this morning so I loaded it up and took a test drive. Cold startup is still a bit rough. Low speed driving or really any gear when the rpms are around 1,000 has some surging. But the high rpm in gear at low speed isn't there any longer.

Throttle response crispness is much improved but could use some more work, I think. Only wound it out a little bit in fourth gear, but mostly just took it easy and enjoyed the drive.

Showing some AFR spikes where it gets lean in a few spots, usually after light gas pedal pressure at cruising speed with low rpms. Like 18.00:1 or so. Short Term Fuel Trims dip way down into the minus figures at the same time.

Ah, but it's getting there. It's very driveable as is, but still some rough edges that I hope won't take too much time and effort to smooth out. Besides, the more miles I get on the car this was the more it will build up my confidence that the car won't just up and die on me.
 
For a side note on tires, I'd look no further than the Nitto NT 555R II Extreme...if you want some serious stick rain or shine (well at least some stick in the rain). I know guys that use this tire as their HPDE rain tire and also autocross very well rain or shine. You get darn near R-compound stick'em, but complete streetability...they just won't last long (~10K miles). They also make this in a drag tire if you aren't worried about great corner grip.
 
Yeah, I had Michelin PS2s on the car originally, and I can't complain about them. After that blow out on Connie's car, I would actually consider run-flats if I could find them in C5 Z06 sizes. Had that happened to the C5Z, the car would have likely had to be towed just to have the tire replaced. And who knows how long to get one in, as likely no one local carries them in stock around here.
 
Rich Z said:
Hmm, I'm looking at the log and I'm only seeing 125 kPa right before traction control stepped in. :shrug01:
Click to expand...

So I found what I think is the formula to determine boost from the MAP reading: boost in psi = (SAE.MAP in kPa - 101)/6.895. So according to this the boost I was hitting then was 3.48 psi. **101 kPa is approximately the barometric pressure at sea level.

When I took the car out on Monday, I hit 157 kPa on the MAP sensor, so that works out to 8.12 psi of boost.

Now as for the SAE.MAP value in the data page of EFILive, which shows a MAX of 22.5 psi, barometric pressure at sea level in PSI is approximately 14.7 psi. So subtracting 14.7 psi from 22.5 psi gives us 7.8 psi of boost. Plus or minus...

I'm presuming the barometric pressure here is approximately sea level, but obviously that value will change depending on the weather somewhat.

So the error I was making trying to determine the boost was because I wasn't paying attention to the name of the actual sensor being used to determine boost: MAP Sensor = Manifold Absolute Pressure Sensor. It's NOT a relative pressure, so barometric pressure has to be taken into account.

OK, so I learned something today.... :thumbsup:
 
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I got a new tune from Mike Carnahan earlier in the week, but today was the first chance I had to load it up and take the car out for a test drive.

Cold startup was a lot better. Not as rough and not nearly the stumbling it had with the earlier tunes. So that was a good sign of things to come, I thought. :thumbsup:

Car just felt stronger to me and sounded stronger somehow. Still a minor problem with throttle crispness just when the gas pedal is depressed in the 1500 to 2200 rpm range, but then it seems to snap together with just a little bit more pressure on the pedal. Definitely improved though. And there is still that minor surging at around 1,000 rpm or less. But overall it feels pretty darn strong.

So I tried to get some logging while the engine was under boost more so than I have done before this time out.



Quite honestly, the car kind of startled me at speed when it felt like the steering got loose on me. I was expecting the rear tires to maybe break loose, but wasn't prepared for the front tires to feel like they weren't exactly gripping the pavement. Maybe it was just my imagination. Or maybe it was just the road itself. But it sure as heck felt strange. And just a tad bit unsettling, even. And heck, I only went as much as 51 percent throttle the entire time. I've NEVER had the throttle to 100 percent yet.

Speaking of strange, I was cruising back towards home and was on a flat section of road running around 65 mph in sixth gear and I noticed the gas mileage was at 33 mpg. :eek: Man, can't complain about THAT!

So all in all, things seem to be pulling together rather nicely with the tuning.

Oh, and the airbridge couplers appear to have held together OK, but I'm still planning on working on that to get it more bulletproof.
 
Dang Rich that sounds awesome and 33 mpg at 65MPH is amazing. Time to put some drag slicks on take it to the track and see what that beast can do. Are there any standing mile top speed events in your future? I would bet that car could do the 200 MPH mark.
 
Wow that is impressive. I am not familiar with the way you are tuning. I know on my LT1 when I do something the ECM has a relearning curve of about 30 miles. By using a laptop program is it instant change or do you also have a learning curve for the ecm. I ask because of my basic curioisity. I am old school were you adjusted the idle screw or the air flow etc until it seemed right. In others word I am a shadetree kind of guy get it gas and air and spark and it will run. You don't say what the speed was when you were on it just a little but I wouild guess somewhere between 70 & 80.
 
Hey Rich, the car sounds great...The cam in the car is causing some surging...You may never get it all out...The tuner would have to spend a great deal of time trying to get it to as minimal as possible...Won't hurt anything...Can be a little bit of a pain in stop and go traffic. But, out where you are, the traffic is at a minimum I would think...Enjoy...:icon_cheers:
 
CorvetteJohn said:
Wow that is impressive. I am not familiar with the way you are tuning. I know on my LT1 when I do something the ECM has a relearning curve of about 30 miles. By using a laptop program is it instant change or do you also have a learning curve for the ecm. I ask because of my basic curioisity. I am old school were you adjusted the idle screw or the air flow etc until it seemed right. In others word I am a shadetree kind of guy get it gas and air and spark and it will run. You don't say what the speed was when you were on it just a little but I wouild guess somewhere between 70 & 80.
Click to expand...

Mike Carnahan has disabled the long term fuel trims because he says it interferes with the WOT tuning in some fashion. I'm not even going to try to pretend that I understand what he is talking about quite yet. So basically the air/fuel mixture is using the values in the relevant tables plus the feedback the oxygen sensors provide for the short term fuel trims. So it appears that there really isn't any learning curve taking place, which I believe is normally a result of changes in the long term fuel trim values. As far as I know neither the code nor the tuning tables being altered by the actual tuning process are self modifying by the PCM on the fly. So the tuning changes pretty much kick in right away once the new tune is flashed into the PCM.

Well, thinking about it, maybe I misunderstood Mike and he has disabled the LTFTs because of that learning curve issue and he will re-enable them after the tuning is all finished. :shrug01: Otherwise when I take the car out, it certainly would complicate things and considerably lengthen out the amount of time I had to do logging. So it really would make sense to do it that way.

BTW, I am using EFILive for the tuning.

As for how fast I was going, well I've been thinking about this, and maybe it's really not a good idea for me to be admitting such things in an open forum... :hehehe: No telling if this sort of info could be used against me somehow if the wrong person reads it.
 
ironhorse said:
Hey Rich, the car sounds great...The cam in the car is causing some surging...You may never get it all out...The tuner would have to spend a great deal of time trying to get it to as minimal as possible...Won't hurt anything...Can be a little bit of a pain in stop and go traffic. But, out where you are, the traffic is at a minimum I would think...Enjoy...:icon_cheers:
Click to expand...

Yeah, maybe so. Perhaps that will be something I can play with on my own to get my feet wet in this tuning stuff. Actually the cam in the engine really isn't radical at all, and others have even referred to it as a "baby cam". It's designed for turbos, and I purposely didn't want it to tilt the balance of power up into the upper RPM range anyway. I prefer low and mid range torque provided by the NA engine, and then let the turbos provide what is needed up on the high end when they get spooled up. This just seemed like a logical design approach to me.
 
Rich Z said:
Mike Carnahan has disabled the long term fuel trims because he says it interferes with the WOT tuning in some fashion. I'm not even going to try to pretend that I understand what he is talking about quite yet. So basically the air/fuel mixture is using the values in the relevant tables plus the feedback the oxygen sensors provide for the short term fuel trims. So it appears that there really isn't any learning curve taking place, which I believe is normally a result of changes in the long term fuel trim values. As far as I know neither the code nor the tuning tables being altered by the actual tuning process are self modifying by the PCM on the fly. So the tuning changes pretty much kick in right away once the new tune is flashed into the PCM.

Well, thinking about it, maybe I misunderstood Mike and he has disabled the LTFTs because of that learning curve issue and he will re-enable them after the tuning is all finished. :shrug01: Otherwise when I take the car out, it certainly would complicate things and considerably lengthen out the amount of time I had to do logging. So it really would make sense to do it that way.

BTW, I am using EFILive for the tuning.

As for how fast I was going, well I've been thinking about this, and maybe it's really not a good idea for me to be admitting such things in an open forum... :hehehe: No telling if this sort of info could be used against me somehow if the wrong person reads it.
Click to expand...

UNDERSTOOD I thought about that after I posted
 
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