Is it possible to change my 89 L98 350 to speed Density. if so, can someone explain how it is done? (Teaching point needed.)


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1989 Pontiac Formula L98 Ported Plenum, Edelbrock 6085 Heads, Edelbrock HI-FLO Intake, BBK 52MM TB, Edelbrock TES, FlowMaster 3" Exhaust, Dual Cats, 3.27 Gear, CompuCam 2032 Cam, 1.5 Rollers, Ed Wright FastChip, Accel Super Coil, MSD 8mm Wires

 

You will need a Speed Density computer. ANd the Sensors and wireing Harness. Other than that your other components should work. YOu will have to either modify or replace on part of the INtake set up, either Plenum or Intake manifold, not sure witch. I wouldn't advise this. IT will get costly for not that much improovement. Plus the MAF system is a little bit more agreeable with mods with out a custom chip.

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86 Trans Am 355 TPI Rebuilt 700R4 with Corvette servo, modified valve body, and a B&M Torque Converter (2000 rpm stall w/ lock up), 87 350 block bored .30 with new crank, bearings, rings, and magnafluxed rods. Reworked 305 heads with 3-angle valve job. Added in the rebuild was an SLP TPI cam, BBK 58mm Throttle Body,SVO 24# injectors,MSD 6A, Hypertech Power Coil, 1.5 Crane roller tipped rocker arms, SLP Intake Runners and Port matching in upper intake including fully ported plenum, TPIS adjustable fuel pressure regulator @ 46psi, Hooker shorty style headers w/ Thermotech heat wrapping, Custom 3” exhaust with Flowmaster muffler and chrome quad tips, Hypertech Thermomaster Computer chip, K&N open element cone filter on modified MAF per TPIS specs, MSD Wires, removal of A/C hardware and a 1LE firewall cover installed. Also there has been a PST front suspension kit with Hotchkis strut tower brace
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Kills:
95 Talon TSI, 96 Probe GT, 91 T/A L98, 89 RS, 86 Mustang GT, 88 Mustang LX 5.0, 92 Thunderbird V8. couple or ricers that I think were Civics or Preludes not sure what year, 95 Celica GT-S, 94 Chevy 1/4 ton 350, one of those NASCAR F150's

 

If you are interested in switching to SD, speak to Grumpy on the PROM board. He is a big advocate of converting from MAF to SD (and he know his stuff).

When you get into PROM buring, you quickly learn the limitations of the 165 ecm and MAF. The biggest limitation is that the MAF can only read up to 255 gm/sec. If you start to produce serious HP, the MAF gets maxed out and you are now fighting the ecm. MAF is only good for mild mods IMO. Read the PROM Board and you'll quickly see that SD / 730 ecm is preferred over the MAF/165 ecm.

I suspect you are asking this question because you do plan to produce serious HP and want to avoid the 255 gm/sec limitation.

Lastly, it really isn't that hard to convert to SD either. The 730 ecm is readily available from an early 90s MPFI 3.1V6 car (except W-body). The only thing different between that and a TPI L98/LB9 is the PROM.

There are plenty of $8D bins available to burn you the PROM for the car.

But if you are just planning to mildly mod your car, stick with your MAF/165 ecm. Though burning your own PROM is still recommended to get optimal results.

 

When I did my Carb to TPI conversion, I used an '85 TPI assembly, a 1227730 (730) ECM, and '92 factory PROM. I did cheat and use a Painless Wiring wiring harness, but your exhisting harness can be moddified with the proper connectors to fit the 730 ECM. My car runs like a raped ape for only being an LG4 base engine w/ stock exhaust manifolds and the like.

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'87 Trans Am
S/D TPI retrofit including functional PassKey, 22# injectors,
JET AFPR, Ported Plenum,
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'97 Bonneville SSE

 

You need to plan this out, the more planning the easier it is. Get a pinout of your ecm and a 92 Fbodies ecm.
IF your good at soldering, it ain't no big deal.
You'll need a 1227730 ecm. They were used in lots of FWD cars. Also, grab the connectors and about a foot of wiring off of the ecm.
You'll need the right calibration, which means a buy at a dealer to get one close to what you have.
If you want the perfect car, I'd suggest doing some reading on the Prom Board. Lots of guys startin to hang out there with good info..
The only sensor you need to add is the MAP. You can then be creative, and use the MAF wiring for the MAP.
If you sub to GMECM, I think there is a guy even selling the adapter to do this.
You'll need a memcal with out VATS.