Spitfire 3500

[Spitfire]

Thanks, i was pretty close to the weight.

Here's a bit of Photoshop magic, I added the hood scoop to a picture I found on the web, mine will be metallic silver instead of black and I'm deleting the chrome strips on the fender line front and back as well as all factory lettering and insignia.

[Spitfire]

I'm in the process of finalizing my parts list and have noticed that depending on the LX9 donor vehicles exhaust layout there can be one or two O2 sensors present. I originally wanted to run a dual 2.5" exhaust with a crossover and 2 heated sensors (one in each collector) but haven't found an ECM (OBD2) that supports this layout in my (Google) searching.

I then thought of using a dual 2.5" into 3" Flowmaster Y collector, 1 heated sensor, and a 3 chambered Summit race muffler with 3"x 2.25" dual outlets, or I could just use a 3"x 3" muffler and single exhaust pipe - which way is the best to go?

I'm open to any other suggestions you guys might have, I know through reading here that most of you are using the 7730 OBD I ECM and an early harness but I haven't been able to find the early harness on Ebay which is why I'm planning on using the OBD II ECM and a MAF sensor. I haven't hit the local wrecking yards yet.

I really want this to be as simple and painless as possible but don't have a huge amount of money to throw at the drive train, being as old as it is and the fact that the previous owner (dumb-ass) let it set out in the weather for so long means that buying or fabricating the body panels and getting the welding done in addition to the cost of parts will eat up a significant part of my budget. ($7500.00)

[3400-95-Modified]

Any ECM that came with that configuration in the stock car will run that... 04 Malibu comes to mind, they came stock with 2 o2 sensors... Also I know many other ECM's when scanned you can still see a LTFT for Bank 2 and a pid for O2 sensor voltage Bank 2, so others may also support it if you can figure out what pins it uses.

[Superdave]

you can probably grab a OBD1 harness from a Beretta or Cavalier with the ECM for around $50 at the junk yard. There really is no need to run dual o2's in a setup like this, especially with a heated one.


3" is a bit large for this engine but you'll have plenty of room to grow. Be prepared, it's going to be very loud.

[Spitfire]

If I go with the 3"x 2.25" dual outlet it won't be too large or too loud will it? The 3" section of the Y collector is only about 18" long.

A question about the ECM and harness from a Beretta, you are running a speed density system aren't you - which makes better power the SD or MAF, or is the difference negligible?

[3400-95-Modified]

No, 94-95 was speed density, 96 was MAF OBDII... I'm currently running a 97 Venture ECM on my OBDII wiring, unchanged.

Some say SD is easier to tune, others think MAF is better.... My turbo legacy is a MAF system and you'll hear about some WRX guys switching to SD and I just can't fathom why, or even what the benefit is.

I like my MAF setup since it knows exactly how much air is flowing in and changing the A/F is very easy now that all my tables are scaled appropriately.

[ForcedFirebird]

It's because MAF doesn't recognize boost and can't compensate timing accordingly like a SD system can.

[3400-95-Modified]

I don't think thats true for the newer OBDII systems... It just doesn't make sense to say a engine control system that utilizes both a MAP sensor and a MAF sensor can't register positive pressure and air flow at the same time. And/or have the same controls or ability to control spark the same way as the previous systems.

I've read that the real reason why people switch to SD on a high boosted vehicle is the sheer limitation of the MAF sensor itself not being able to measure that amount of air flow... But even today I think that can be overcome with different sensors and different engine control systems.

I have a feeling that SD systems are being treated as the next "Carb"... Some will just prefer to tune with that setup and like its results more than switching to a MAF system if one is available for what they are doing and will suffice in its ability to measure enough flow.