3900 swap into Fiero

[Joseph Upson]

Another yes vote for the race mufflers. They sound very good. Anxious to see what that beast will do.

I am having a hard time getting my head wrapped around what effects the cam travels will have on performance and how it is used to eliminate the EGR. The exhaust residue in the LZ9 LIM that I have suggests that, at some position, the cam timing allows exhaust to go into the intake and makes me wonder if the higher exhaust pressure of a turbo will have an adverse effect when the VVT is at max travel. Maybe... just maybe I think too damn much.

Anyway... great to see that you are making progress Joseph.

From what I've read it's actually the advance that gives the 3900 its EGR effect and are you sure the residue in the intake is not from the PCV feed since it feeds top center of the intake plenum?

In case I didn't mention it here my cylinder pressures are all in the 213-235 range with 4 cylinders at least 220 and the last two cylinders to be tested 5 & 6 213 as a result of the cam advance.

You and I discussed some time ago a difference in the cam specs you measured vs. what Delta camshafts told me. I was given the impression the stock cam specs were a bit narrow in the LSA and that would make sense given I read in my camshaft & valve train book that a narrow LSA favors the EGR effect which could explain what you are seeing in your engine.

When I setup the engine I found that retarding the cam really isn't retarding it much at all but more like putting it in the straight up position since at TDC the intake valve starts to open just as the crank starts to turn off of TDC, suggesting the engine was cammed for peak output with the cam fully retarded and likewise fully advanced with a transition in the middle moving from idle rpm to max rpm.

My reground cam however is cut for high end performance so the intake valve doesn't open until the crank is turned a few degrees off of TDC. Before I had instances of low to no power brakes coming to a stop so starting the cam in the parked/stock position should make for a great improvement.

I'll post a video of the VVT effect at idle later. My dyno simulations show that the engine should produce 350 hp 0n 7 psi at 6500 with the cam parked and 416 hp retarded. I'll look at the simulated static cylinder pressures vs. actual later although they will not be comparable due to the associated engine speeds.

I should have test drive video today.

[CNCguy]

I'm pretty sure about the source of the residue as the UIM is very clean neat the PVC port and there is more buildup as you get closer to the intake valve. It would be logical that advancing the cam would create the EGR effect but I wasn't sure if I was overlooking something.

By chance, did you check compression with the cam retarded? Just curious what effect it would have.

Looking forward to your new videos.

[Joseph Upson]

I'm pretty sure about the source of the residue as the UIM is very clean neat the PVC port and there is more buildup as you get closer to the intake valve. It would be logical that advancing the cam would create the EGR effect but I wasn't sure if I was overlooking something.

By chance, did you check compression with the cam retarded? Just curious what effect it would have.

Looking forward to your new videos.

I wish I had checked the compression while the cam was retarded. I'm sure it was lower as the idle vacuum is significantly increased, I'm estimating having it ready for a test drive in about 2 hrs. I'm definately planning to take it with me today unless the test drive is problematic.

[bob442]

tempting to see...

[ForcedFirebird]

Man, I loke those mufflers, silencers not as much.

Is it me, or does your shoes look like the are on the wrong feet at 30sec in the vid? haha

Give me butterflies in my belly watching your beast finally come to life. I can't wait until we both have that wonderful spooling sound coming from our cars.

What kind of idle RPM are you seeing? The lope when the motor dropped RPM after letting go of the throttle made that cam sound so much nicer, but my have been just because it was about to stall?

What are your cam specs, and how much will it retard? I'm sure it's around here somewhere...

[IsaacHayes]

"Silencers" look restrictive!

[Joseph Upson]

Man, I loke those mufflers, silencers not as much.

Is it me, or does your shoes look like the are on the wrong feet at 30sec in the vid? haha

Give me butterflies in my belly watching your beast finally come to life. I can't wait until we both have that wonderful spooling sound coming from our cars.

What kind of idle RPM are you seeing? The lope when the motor dropped RPM after letting go of the throttle made that cam sound so much nicer, but my have been just because it was about to stall?

What are your cam specs, and how much will it retard? I'm sure it's around here somewhere...

I knew that was coming because I thought the same thing about the shoes when I saw them in the video.

I didn't do any tuning at all this go around, ran out of time again. The custom fitting of parts takes up an enormoust amount of time. The engine wasn't going to stall, I thought it was but it didn't. It actually idles around 900 rpm but that's affected by a slight tension on the throttle since the cable is not properly positioned and seated yet.

The cam specs should be in the photo line-up if I recall correctly and as far as retarding the cam goes it is actually advanced by default so that when it is retarded it goes to about a straight-up install position which in my case is about -5 deg since it was reground.


I purchased the silencers because I thought those straight through mufflers were going to be loud, I'm still amazed at how much hush-power they have despite not having any baffles inside, just small perforations in the tube. The silencers are an after thought now.

[Joseph Upson]

I ran out of time again, the little odds and ends wore me out. I did get front mount intercooler circuit completed though. I'm not frustrated since several deficiencies were present that would have set me way back had I driven the car before finding them. While letting the engine idle for about an hour looking for problems, I found an oil leak and the next morning a massive water leak that resulted from a loose clamp and a loose oil sending unit.

Then I discovered by accident I was revving the engine with one of the turbo compressor housings barely finger tight on one of six bolts, the others were all loose. I melted a wire loom around the ignition module wires and even worse a shift cable so although by the time I shut everything down last night I had nearly completed the install for a test drive, I couldn't go anywhere no matter what.

I believe it's going to be a lot more impressive than just a tire chirp on the first and second shift. I didn't take many pictures but hope to be home again in two weeks to put it to the test.

[CjLink]

i dont know if it ever got mentioned, but i'm reading my stock 3.9 injectors at 30 pounds an hour (hptuners)... if you got the 8.1Lers to fit then there have been some guys running these injectors in their 8.1s over on hptuners -

http://www.bmotorsports.com/shop/product_info.php/cPath/144_146/products_id/574

i dunno how you're not running out of duty cycle but i'm hitting 75% DC at 6500rpms... at 5000ft elevation

[Joseph Upson]

i dont know if it ever got mentioned, but i'm reading my stock 3.9 injectors at 30 pounds an hour (hptuners)... if you got the 8.1Lers to fit then there have been some guys running these injectors in their 8.1s over on hptuners -

http://www.bmotorsports.com/shop/product_info.php/cPath/144_146/products_id/574

i dunno how you're not running out of duty cycle but i'm hitting 75% DC at 6500rpms... at 5000ft elevation

The stock 3900 injectors are rated at about 28 lb/hr barely, the 8.1 injectors are 30 lb/hr at 43.5 psi, I'm running about 55 psi at the rail so I have the equivalent of about 33 lb/hr injectors. Since I'm only runinning about 40% more power I should have sufficient reserve given your stock 25% remaining duty cycle and my ~20% capacity increase.

There will also be an increase up to a point under boost when the regulator senses the boost pressure. My AFR gauge has never indicated a lean point at 7psi and if and when the injectors are out boosted I have a set of 60s to go in place.

I'll be test driving it some time today.

[Joseph Upson]

Finally got around to testdriving but with no tuning to maximize performance. Verdict, down right impressive, the cam advance did excactly what I was expecting it to for the offline performance, it doesn't chirp the tires in first and second gear as easily as before partly because the tire pressure is low and traction is better, however it doesn't use the flywheel inertia the way it did before to cause that chirp, it pulls and sustains and although I didn't catch the first testdrive on tape to show it, it nearly got sideways once on acceleration.

I've owned a TPI 350 Fiero and TPI 383 stroker Z28 and neither was this fast. The boost gauge is showing about about 9 psi but the MAP sensor is showing a max of 152 Kpa which is a tad over 7 psi which is about 1 psi below the wastegate spring pressure.

I'll post video tomorrow since I'm about to hit the road headed back. I have an example of the VVT effect but the car is so fast with the cam advanced, that due to being reground to high performance specs I might not need the benefit of the VVT for higher output. I'm certain beyond a doubt that this engine is putting out over 300 hp given how hard it pulls throughout the rpm range.

The front mount intercooler cut the intake air temps by more than half of previous temps on an 80 degree day as you will see in the screen shots below. Previously the intake temps as you can see above in a previous post were around 100 deg C or 212 deg F at 7 psi, during the test runs the inlet temps reached a maximum of about 42 deg C, 107 deg F, and that was idling in the driveway after the second testdrive. Note the 38 deg C at 7 psi. I'm not taking the car yet because it needs to be tuned. You can see the timing retard due to the lean condition. I expect it to be a little lean up top due to the cam position change and the higher efficiency shift to the right (lower rpm), I wasn't expecting it to be that lean though, good thing I used premium fuel to avoid a serious detonation event.

Hopefully the next trip home will be the one that completes it.

[IsaacHayes]

Yes yes yes we all are waiting for some new video.... Getting closer. That intercooler made a HELL of a difference!!! Much better!!!

Are the charge pipes going to the FMIC metal or some sort of rubber? having all metal pipes would add more to releasing the heat I would think.

[Joseph Upson]

There was some concern from members that there would be turbo lag as a result of the intercooler location, after a few acceleration tests I can say not at all, especially when you consider the spool up time changed for the better by the turbos remaining close to the engine and being attached to headers in place of the previous manifolds.

There is a rule of thumb stating you can expect a 1% power increase for every 10 deg F the intake air temps drop, so 212 deg F down to the current 100 deg F suggests I gained a 10% power increase plus what the headers have to offer.

Even in a poor state of tune where the engine stumbles a bit when launched from idle it was impressive. Once that's ironed out and the methods linked to on stopping wastegate creep linked to under the boost topics is applied it should be even faster on 7 psi.

It is very lean in some areas and I attribute that partly to the cam position change and pulling 3 points from the BPC before the test drive. The ~1.5 deg of timing retard that occured under boost was at a high INT reading as can be seen in the screenshots above indicating a very lean spot and also apparently good reserve indicating 10 psi or more should be easily attainable without using my water/meth injection kit.

I can't do the performance justice with a description, it is simply a much stronger runner now than before and will need to go on the dyno to justify any projected benefit from retarding the cam at higher rpm since I felt no power fall off winding up to over 6k with the cam fully advanced and that maybe because it has been reground to high rpm performance specs.

At 6 minutes in the video the effects of VVT are demonstrated.

http://user.streetfire.net/video/Latest-test-with-and_638353.htm

[IsaacHayes]

Yeah I was going to say for 7 psi and that lean 1.5 degree pulled is not a whole lot. I'll have to check the video later.

[Joseph Upson]

Here is a link to a shortened version of the above video that hasn't completed processing yet. Tuning modifications is very important and I'm sure the engine has a lot more in it on such a mild level of boost once the fuel and spark table is optimized. While idling without mufflers the engine had an rpm fluctuation that went away as soon as the mufflers were installed. Next trip I'll try to do a testdrive with open exhaust to see what the difference is.

http://user.streetfire.net/video/Upgrades-short-version_638461.htm