Spitfire 3500

[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.

[ForcedFirebird]

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

[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.

[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?

[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.

[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.

[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)

[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.

[ForcedFirebird]

As far as weight goes I've even sandbagged it a bit with 35 extra Lbs just in case I go over what I've calculated the final weight of the car and myself to be. I also went with 340 Lbs engine weight even though the information I have is 350 Lbs because I won't be running PS or AC and I figured I would lose at least 10 Lbs that way.

I weighed a 3500 without P/S, A/C or alternator. It was 340lbs with the stock cast iron exhaust manifolds...

http://60degreev6.com/forum/showthre...l-LX9-Weigh-in

[Spitfire]

Heh, those numbers are with a 2500RPM launch, when I switched to 3500 RPM they came out as a 11.535 @ 120.2 mph and 0-60 in 3.541 seconds.

Oops, the above numbers are with the Cadillac CTS 6 speed transmission, I forgot to change it back to the T-5 gear box.

With the T-5 and a 3500 RPM launch I got a 11.547 @ 120.0 mph and 0-60 in 3.573 seconds, 0-100 mph in 7.987 seconds - not too shabby.

As far as weight goes I've even sandbagged it a bit with 35 extra Lbs just in case I go over what I've calculated the final weight of the car and myself to be. I also went with 340 Lbs engine weight even though the information I have is 350 Lbs because I won't be running PS or AC and I figured I would lose at least 10 Lbs that way.

[Superdave]

man, that's not bad at all. I wish my car was that light... I'd be in the 10's.

[Spitfire]

Thanks Dave, that means Desktop Dyno is pretty close,it extrapolated 238/268, (HP/TQ) EA Pro gave me 262/284 @ the crank.

I thought it might be the other way round since EA Pro allows you to be more precise on the inputs and DD is pretty generic in that regard.

Using those numbers in Dragstrip 2003 gives me an 11.66 @ 120mph in the 1/4 mile and 0-60 in 3.720 secs, not bad at all. .

[Superdave]

i've dyno tuned similar builds and around 210 WHP is where they end up with a manual trans. probably around 240 ish @ the crank.

[Spitfire]

I have Desktop Dyno 2003 and Engine Analyzer Pro 3.3 and get wildly varying results program to program.

How much HP/TQ can I realistically expect from an LX9 with a 65mm TB, high flow MAF, 27Lb injectors, ram air CAI, a high octane tune, (OBD II) and equal length headers?

[3400-95-Modified]

Ok sounds cool.