3900 swap into Fiero

[ForcedFirebird]

That thing definately has some torque. The front end raising looks a lot like my neighbor's 327 Fiero (350hp crate) when I rode in it.

I can't wait for you to finalize the tune and really get on it

[Joseph Upson]

That thing definately has some torque. The front end raising looks a lot like my neighbor's 327 Fiero (350hp crate) when I rode in it.

I can't wait for you to finalize the tune and really get on it

It has a lot more in it, I just discovered in a bin comparison that I reduced spark timing by about 3 degrees or more as a precaution at 7 psi above 3000 rpm so that definately had a power reducing effect. Since the engine showed a lot of reserve against detonation despite being very lean in some boost areas it should have quite a bit of improvement left in it once tuned properly without upping the boost right away. 10 psi should make it very interesting to drive, 15 will very likely be scary as twice it has nearly gotten sideways on me.

[Joseph Upson]

Here are a couple of pictures lifted from the part of the video that was edited out. I have about 80% intercooler efficiency using a 27x6x3.5 unit with a 19" long core if I recall correctly. After install I realized I could have gone with a 7" to 8" tall unit but they are hard to find at the price I paid with the tank fittings centered. Hopefully the water/meth kit will bring me very close to 100%. My compressor efficiency will actually climb as I turn the boost up, right now it is at about 55% at 7 psi, that's why the non intercooled air temps were so high at 212 F. Turbocalc is pretty close to the values I'm seeing and it shows with my turbos that compressor efficiency will not improve above 70% until at least 10 psi is reached so my air temps should hold steady or decrease as boost is increased.

[Joseph Upson]

Still didn't get much if any tuning done although some extremely lean areas in the low rpm range were cleared up and probably pushed to the opposite extreme.
Advance Auto Parts shift cables need to be replaced with better quality cables, they are not rigid enough and can not take the heat, I left the car with a seized selector cable. You can note the delay between the 1-2 shift at the beginning of the video due to flimsy shift cables.

On a half tank of 87 octane the car ran very strong at what appeared to be as much as 8 psi, there is plenty of room for improvement at that boost level with higher octane fuel and installation of the alcohol injection kit. The two changes together should make 15 psi very easy and probably attainable with just one or the other. 12 psi should be more than enough given how strong it runs at 7psi.

Unfortunately the datalogs were saved to a corrupt file I discovered a little while ago so I have nothing to take snap shots of to show inlet temps and boost pressure.

I removed the mufflers as a precaution since the body supports have not been installed yet. Hopefully it will be finished by the end of the year.


http://videos.streetfire.net/video/T...out_680592.htm

[Joseph Upson]

I'm now in the process of changing over to a single turbo setup from the twins. I did a few runs with the GTech installed and if CNCguy is correct and I do believe he is, the cam is advanced entirely too far. The GTech is pretty accurate from track testing I observed and it measures net horsepower which is a little less than dyno testing at the wheels.

The car felt very fast but it is nowhere near as fast as it should be 202hp and 250 lb/ft all at just over 4000 rpm which is 2000 rpm short of what it should be peaking at, a sign the cam position is limiting power. When I retarded the cam it ran even worse with both power and torque under 200. I'll be degreeing the cam in ofcourse and I'm sure there was more power in it had it been tuned, it was rich on the top end and set a code 45. In Desktop Dyno the max I could advance the cam is 15 deg and that dropped power at 7psi down to about 300, CNCguy said full advance is about 30 deg so the additional 15 I can't test in the program along with a poor tune makes it about right although I believe Desktop does power at the crank. I'll be testing it again after the turbo install and cam degree in to see what happens.

[CNCguy]

Good to see you back on your car. I'm curious to see what numbers you get when you degree the cam in and how they compare to the numbers from the CMM.

[Joseph Upson]

Good to see you back on your car. I'm curious to see what numbers you get when you degree the cam in and how they compare to the numbers from the CMM.

I believe the timing under boost is too conservative also, I'm still ecstatic that the few incidents of knock retard of about 1.5 deg all occured around idle rpm where I know the timing is too far advanced above stock Turbo Grand Prix timing. I put 2.5 gal of 88 octane fuel in it after the tank closed in on empty so there is plenty of room for boost, the test runs were made with that fuel grade. The manifold modification for the turbo is comming along well and I expect to have it installed tomorrow. The setup is much, much, much cleaner now with the turbo hidden partially under the trunk and a crossover pipe tucked neatly over the bellhousing an added bonus is the air filters used for the twins are universal and will clamp right on the 4" inlet of the T67 turbo.

I just hope correcting the cam produces the expected improvement.

[Joseph Upson]

Forgot to mention there was an exhaust leak at 3 of the header ports loud enough to hear in the car.

[Joseph Upson]

The flange is welded up, the exhaust should be relatively short. I'll have to divide the 3" pipe into dual 2.25" outlets which shouldn't be too tuff since the engine and cradle will be removed for cam degreeing and flywheel install.

I had to figure out a way to lock the dual mass flywheel and after giving it some thought I found myself at the machine shop. I had the pressure plate bolt holes chased all the way down through the base to stake the top half of the flywheel to the bottom. Some dual mass flywheels are torque limited and will slip, that's the reason for this modification. The top half is not tightened to the bottom, the screws just thread down into the bottom half but tighten against the pressure plate.

[robertisaar]

the flywheel slips? WTF?