ZZ3Astro

Everything is on but the SFC's. Now I can tell the holeshot converter is much too tight. I was trying to get the flash rpm down into the power band but I knew the 2400 would be real tight on the bottom end. Since I was having so many issues from 30 feet and out, I wasn't too worried about a bit of lag on the launch. But now it is very obvious and will cripple my 60 foot. I think I'll see a 1.75-1.80 at best. Guess it's time to figure out a plan with this PTC converter ASAP. I have a street event in three weeks and a score to settle with a certain truck!

RaverRacerX

anyway you can get a hold of a looser converter before the grudge match?

ZZ3Astro

Yes I can and will put the PTC or Vigilante back on this week if my 60 foots and trap speed don't impress me. Probably the vig so I can send this pos PTC back for a free re-stall. I know it won't get down to what I originally asked for but maybe they can tweak a little more tightness out of it. They sure didn't listen to me during the order.

Drac0nic

Dumb question what lines do you have to the reg? Are they soft? Ever checked boost at the reg to make sure pressure was not rolling off?

Street Lethal

iTrader: (16)

...

ZZ3Astro

So this converter is a definite fail on stickies. I was stuck at 2.0 and finally eeked a 1.97 out of it. Pathetic. The car went 93 mph and 7.94, right where it likes to be. However this was accomplished only by increasing boost to 19 psi. Still a good showing on a 2.0 sixty though. I had two problems. One early hot-lap ran into the hot-lean condition. A thorough cooling resolved that. And then later a new break up problem that only occurs in the last 150 feet of the run. You can hot lap it and the second lap will be fine. Feels like one plug going out. Another impossible to narrow down gremlin.

I'm pretty much over this engine. I'm not will to dump any real money into it to resolve this nonsense. A simple 5.3 swap will do wonders for many of my issues.

I have the factory short hard line from the back of the plenum into the reg with zipties on just to make sure. I've also ran an external regulator with totally different tubing, but it failed from the underhood heat and the pressure rolled off just cruising.

ZZ3Astro

So today I went engine shopping. I can do the whole 4.8 setup for $550 and a 5.3 at $700. Of course then you have all of the swap costs plus an intake and fuel system changes. That is not to mention the AC lines. And it is an unknown... if the engine had problems or whatever. On the plus side, I have a lot of good Gen 1 parts to sell and offset the most of cost of the swap.

However, the original mission of this car was to do this with TPI. I keep going back to the posts about the turbo manifold back pressure. My pressure ratio is 2.3:1 at 20 psi. It seems like the turbo is a cork and it's plugging up my output power! So I convinced myself to find a way to make a 76mm fit for a test (remove hood, space turbo out with spare T4 flange etc). But then I read TurboedTPI's thread yet again and realize he only has a 62mm turbo. How can my $900 67mm Precision be so wrong when he's got a 10 year old Turbonetics seems so right? Precision said it would work for 600-650 hp and he's running a smaller turbo making more hp than that so I'm inclined to believe them. Feeling very lost and confused on this project.

ZZ3Astro

It looks like I have an easy yet major test under way. I borrowed a Precision 76mm turbo and it actually fits with the spare T4 flange added between the turbo and manifold! Now I have to make a slightly longer oil return line and come up with a 3 inch to 2.5 inch silicone coupler, but otherwise a pretty straight forward affair. The down pipe doesn't quite center but it will couple good enough for a short term road test. If I see any improvement at all, I'll know I'm on the right road and I'll start my new header. If it doesn't do anything then I'm going to spend the coin on a 5.3 I think.

Steve

IROCgiraffe

iTrader: (3)

Sounds like a plan!

FIRECHICKEN

iTrader: (3)

What ever happens. You are still my hero. Thanks for blazing the way. More or less

IROCgiraffe

iTrader: (3)

I'm jumping on this train too!

ZZ3Astro

Results are in! I was surprised how easy the 76 install went. The T4 flange 'as a gasket' spaced it out perfectly. The downpipe alignment was a bit off but everything else reached. It rubs the hood insulation more than the 67 and the turbo blanket is not happy with the fit between the turbine housing and the AC line. So what happened?

It won't spool for crap. It made an absolute peak of 10 psi and averages 8, and that is with 4 vacuum tee's to the wastegate and the adjustment about as far in as it will go. This setting made 19.5 psi on the 67. For what its worth, it pulled decent at 8 psi in higher rpm.

Conclusion: Either the manifold is too restrictive or the engine itself has a configuration issue. This is the exact turbo that was on my friend's stockish TPI engine that went 112 mph in the 1/8th. The only differences are the ECM and the headers. He built full headers and I have this fairly restrictive looking log + stock manifold. The gamble is whether headers fix it or if that is yet another waste of cash on this setup.

IROCgiraffe

iTrader: (3)

Go LS!

RaverRacerX

if you arent making the boost you should, there may be other issues to look into from leaks to wg spring pressures, etc.

ZZ3Astro

No leaks. I unbolted the 67 that was making 19.5 the day before and put the 76 on. Just for a little 6:45am fun I tightened the turbo flange bolts even more and went for a drive. I only unbolted a couple of pressure components to do this swap so it's not like I'm troubleshooting an entire turbo setup. Everything is tight and leak free.

Same results on the drive this morning so I just pulled the WG reference line completely off. It peaked to 13.5 psi in the top of second gear but averaged about 11.5 psi. It should feel insane at 13.5 psi. It does pull nice but nowhere near what it should be. Basically it feels about the same as the 67 at that boost + 1 psi maybe and comes in much slower/later.

junkcltr

iTrader: (1)

That 2.3:1 pressure ratio isn't horrible. Not great, but not horrible. Have you ever revved it up to 2500 RPM or so and measured the timing so see if the ECM matches the actual at the crank? What is the AFR in boost tuned to? What do you estimate NA FWHP at? Cam duration and LSA?

ZZ3Astro

There is a timing error that increases with rpm. It's about 3-4 degrees less of real timing than what is in the ECM tables at 5000 rpm, less error with less rpm. My tune right now is quite aggressive with timing to the point it has detonated more than I like, but I've been searching for the missing power at all costs.

Boost AFR depends on the fuel temp. I shoot for 10.9-11.1. If the car is warmed up after driving an hour at night it will often lean to 12.0. If it's a hot summer day it will get much leaner. I've driven it in all of those conditions from 10.0 to 13.2 and the car flattens out (of course) as it gets into the 12's. It seems to like 11.2-11.3 the most.

Based on previous dyno sessions and trap speed, it is all consistent with 415-430 rwhp, so right at 500 fwhp.

Cam is 224/224 on a 114. Hydraulic roller.

project89

iTrader: (1)

have u tried adjusting the ait tables, mine runs perfect but as air temps goes up it started to get leaner, a quick adjustment fixed my issues

Drac0nic

Junk has said something that has enough merit to at least check, I mean it would make a scary amount of sense in a weird way especially with the under hood heat. Something else I'll ask is what are you doing for ignition on this? Timing shifting around could influence AFRs, and a module/box/whatever would be thermally sensitive probably. If you're using a stock HEI module and run into the issue, hit the bottom of the dizzy with some canned air upside down and see if it goes away. Hell hit the FPR with it if that doesn't work and see if it goes away. It's a somewhat common way to "force" an error in electronics troubleshooting.

Dumb point to make here, there's a timing vs temp 2D table that's an option. Usually it's used for cooling, but it may help you out here. Have you been monitoring your tranny temps at all? I'm really wondering if you're dumping the power into the gear box somewhere.

The fact the T76 didn't make any more power and doesn't make higher boost levels really is VERY curious. You have enough engine for it, that's for certain. I thought you were measuring back pressure at the flange, correct?

project89

iTrader: (1)

the megasquirt has a spark latency setting for correcting timing mismatches i.e actual vs commanded)

the iat sensor has a table for fuel added or pulled versus temp that also has to be adjusted or the engine will lean out or could even richen up as temps go up or down

i just had this issue on my car

and yes the 700r4 eats up ALOT of power specially with a looser converter 25% getting eaten up is not uncommon

ZZ3Astro

Yes, but the problem is only relevant to the fuel temperature. It is bad enough that I have a remote thermometer attached to the tank. If the area around the tank exceeds 125, the fuel is over 140-145 degrees and the severe lean condition will occur in boost.

Also I have put resistors in place of the temp sensors to simulate specific conditions, but the problem still occurred based on the overall drivetrain heat soak.

This is a well documented problem on TPI cars in general, but as I've upgraded the fuel system with a 340 pump it seems to only be an issue in high boost. My theory though is that there is more heat under-hood than there should be, which makes the problem show up any time you play hard in 80-90 degree weather. If it's the restrictive manifold, who knows how high the pressure might be further back from the turbo. All of that heat stays compressed at 45+ psi where in a more efficient setup it would go right out through the turbo. A thought at least.

ZZ3Astro

I am running a stock HEI module which feeds timing data to the megasquirt. Ignition is fired through a 6AL. The timing error is always present under all engine conditions. For the FPR, I've replaced it twice and ran external regulators as attempts to resolve. I've routed new fuel lines into the cold start injector fitting. I've replaced four fuel pumps and modified the pickup. When the drivetrain gets heat soaked, the fuel reaches 140+F and fuel delivery capacity diminishes. It's as simple as that. Now with that said, I've never replaced the injectors but considering they are Precision Turbo injectors they aren't cheap junk (maybe expensive junk though!).

I have not monitored tranny temps but the fluid looks as perfect as the day I built the transmission and put it in. Mind you I changed the fluid with the first converter swap, but it was absolutely flawless. Minimal material on the magnet after two years of abuse. Filter clean. No slipping just good solid shifts. I've been through three converters, with the latest being the very tight holeshot 2400. I can only stall it to 1700 before it pushes the locked front tires across the beam.

I'm with you here... The pressure was measured in the center of the flange, which indicated the turbo to be the restriction. I mean the air already had to pass the opening of the flange to get to that measurement location, so....

ZZ3Astro

Yeah spark equipment latency I believe it is called. Mine is maxed out. Before that, the error was 9 degrees at 5000 rpm.

I decided to go ahead and make headers for it. I'm too far down this TPI path to jump ship this close to the end of the project. After doing some math, I can build the headers for under $1500. A proper TPI engine needs matching header tubes to look right anyway. Then if this engine doesn't deliver, I know I'll have the supporting systems for an engine that does. And I can always sell it off in pieces and fund a 5.3 swap.

Place an order tonight for a set of stainless Fbody headers. Once I get them in my hands I'll know if my master plan can work. If not I'll send them back but I think this could turn out pretty nice looking. I'm planning on full headers with collectors rather than a log. I don't want any chance of something with them not being sufficient to do the job and they will look better than a log I hope!

The plan is to use the driver side as is except to modify to have a VBand. Passenger side will get chopped up, tubing flipped almost 180 with a high collector near the alternator also vband. Then a merge tube next to the alternator. Not sure if the turbo will mount high and forward of the current one or more down in the battery tray area.

project89

iTrader: (1)

didnt u try running the car with no hood ? if so did the issue still occur

how about ex system are u running it out the back like factory , maybe some heat shieilding to block the radiant heat from the tank

ZZ3Astro

Haven't gotten around to no hood yet. It's on my TTD list.

Exhaust is all factory layout. Muffler is a straight through Magnaflow. It doesn't seem to hold much heat at all. I'm pretty certain the real heat it coming from the engine bay. You'd better not stand next to the passenger side door with flip flops on! The cooling air up front coming off the engine bay is intense!

IROCgiraffe

iTrader: (3)

Not trying to sound like an a$$, but it sounds like the idea to run the car without the hood should be a priority. It's easy to do and doesn't cost anything... Low hanging fruit?

In all seriousness, I am interested to how it runs without the hood. You've been talking about under hood temps for a while, even in your videos

ZZ3Astro

Well it's not an issue of how it would run cold vs hot. I already know how it runs both ways. I'd love to solve the heat issue, but I think it is something that only affects the TPI engine. If I don't get this thing making some real power soon, there won't be a tpin this car much longer. On the other hand if the headers make a 10 mph difference in trap speeds, I strongly suspect the freed up exhaust will reduce engine bay temps a lot. If not then I'll deal with it.

I think I have my header design pretty well mapped out. I will have to have the pieces in my hands to know if this configuration will fit but it looks workable on paper. But when you get your hands dirty in the engine bay of these cars, you quickly realize how little extra space there is to work with.

ZZ3Astro

I modeled the header design I've got in mind. This is not to scale at all but gives an idea of the passenger side header configuration. The driver side header will mount as designed and the crossover will follow a similar path to my existing setup. There isn't a lot of room to do the merge and 90+ degree bend into the T4 flange, so I made #2 primary into an S to move the collector further back. This gives more room for the merge pipe and vband clamps. I'm thinking it would be wise to switch to solid motor mounts with the turbo mounted so far away from the engine, unless the flex fittings are more than sufficient to absorb the movement.