So what do you think in the end? Was the cost and effort worth it? How's the experience over a carb? I have a TPI setup sitting on my shelf.Originally Posted by Mikey G
So what do you think in the end? Was the cost and effort worth it? How's the experience over a carb? I have a TPI setup sitting on my shelf.
When I got started with this project, I put a carb on for simplicity as I knew there would be much troubleshooting elsewhere in the car. I really liked the TPI I had sitting on the shelf as well. I was convinced the OBDI would work and the idle quality would be acceptable. OBDI (SD),did not have the options to contend with the overlap on my cam. Idle quality was bad - always rich. I had three different people try different things. More research led me to want the OBDII - LS conversion. The local tuner also guaranteed me he could make it purr. I did what I could and got the what I needed from EFI Conversions. The cost was still around 1,200 all said and done + $700 for the dyno tune.
The TPI set-up will make somewhat less HP but is a great torquer - especially at low to medium speeds. Much will depend on how hot is your cam. The OBDI has its limits. So does the TPI. I maxed the porting the plenum and the base manifold, Port matched all connections. and put on a 58mm TB. Power started to drop at 5800.
All in all I think the TPI is a way better looking than a carb or a TB set up. I had a tone of fun with the research and install of both the OBDI and OBDII. I would go straight for the 24X conversion. There will always be options for future add ons. My car was running so I accumulated the parts slowly. The hit was not so severe. More than happy to share any information I have
Hope this helps
I am in the middle of setting up a TPI 383 controlled by a 2006 LS 6.0L PCM in my 1997 Express van.
Will be a 11:1 6" rod 383 with Edelbrock Etec170s, Edelbrock Vortec TPI base that has been ported, Siamese ported SLP runners, ported factory TPI plenum, LT1 throttle body, Doug Thorley tri-y headers, 2.5" dual exhaust into a dual in/single out muffler with electric cutouts. Finally I am using the Lunati Bootlegger 224/236 @ .050 cut on a 108* LSA and it will run on E85 with a flex fuel sensor. The ignition system is EFI Connection 24x with Delco D585 coils.
Timing table is not hard on these setups. Provided there is NO knock activity it will run on the high octane map.
You set up is quite similar to mine. I have 10.5 with 6'' rods. I chose the AFR 195cc. CC Xtreme EFI 280 -m 230/236 with 109°. 1-5/8'' shorty headers with 2.5'' dual cats, mufflers and Morose racing mufflers at the back as resonators. My car is quiet and no drone. I think you are correct with the ease to tune in general. He completed the WOT in 3 pulls. I think this is an awesome combo. Gobs of torque at low and mid range. Perfect for a daily driver - but with sharp teeth.
The coil -on-plug with sequential injection makes the cam seem much less choppy at idle and throttle response is definitely improved over the OBDI or the carb. Many people have a hard time figuring out just what I have under the hood... (Cool).
My tuner also mentioned if I was to switch to wheel bearings with the ABS sensors, he could program the tune to back off when there is wheel spin detected. Great for when one gets stuck in the rain. Just need to be able to turn it off when wanting to fish tail or engaging the line-Lock and doing a smoke show...
Hey Mikey,
My problem is that I'm in Australia, we had one maybe 2 cars that have a Chev Small Block in them (HT I think) and they were back in the 70s with a carb. Everything they tune here is a LSx and there might be maybe a handful at the absolute most of other people here in Australia that have done a 24x conversion.
All the shops I've talked to about tuning it don't have a clue what I'm talking about when I explain the setup, which doesn't instil much confidence.
My main concern is without them knowing about the 24x conversion and just trying to tune the tables like they would for an LS1, they'll
1) Not be able to do it
2) Spend a lot of hours ($$$) trying to tune it
3) Damage the motor
4) Hand it back to me no better and with a 1K+ bill.
If tuning is as simple as doing a run on the dyno, taking the readings and adjusting spark and fuel until the maximum power is obtained, and then extrapolating the values measured into the areas of the map that weren't measured using smoothing or calculations, then it will be fine I guess, so long as he uses the base tune LRT has configured for me, and doesn't start from scratch with a base tune and miss out things like bank assignments etc.
If it requires knowledge and understanding of the differences in the SBC spark requirements and timing then it may be problematic.
There's also the risk of "tuners" just using a library of LS1 motor tunes that they charge an arm and a leg to flash a generic tune which won't come anywhere near what mine needs.
Well I've still got some misfiring issues I think. Going to hit the exhaust ports today with a laser thermometer and see if I can find a cylinder that's not firing.
I also bit the bullet and bought the HP tuners suite and scantool to help diagnose and tune. I installed a fuel pressure gauge, wideband and vacuum gauge, and can now see i've got between 7-11" of vacuum that bounces around wildly, and with the XR270HR cam in a 400SBC, it should be more around the 15-20" and very steady, so I have to go exploring after the misfiring is fixed to see what's causing it.
My next best guess is either a vacuum leak on the intake gasket, or something more sinister like a cam lobe being wiped, collapsed/spun lifter, valve seal or something else mechanical.
From what I've read there's also the possibility the low vacuum is because the valve timing is wrong. I've checked for vacuum leaks outside the motor, so maybe it is in the motor.
Looking to see if you're firing on all cylinders with a temp gun is very useful - correct if required
Check your initial and total timing. Engine can sound quite good but have a low vacuum.
How are you checking for vacuum leaks? What intake you using? - Perhaps a missed open port somewhere? (I've been fooled at least half dozen times )
Let me know,
Mikey G
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