coolraptor

Hello!
Ive been reading for hours on this stuff but something still is not making sense to me, please forgive me if this has been asked a million times...

Here is the plan, Iam switching a high compression 383 to a low compression pt76 boosted setup, trying to figure out what iam going to have to do to get it tuned. Was hoping it is as simple as getting a pcmforless tune to get the engine running then get it dyno tuned, let me know if iam wrong.

Specs it will have:
1995 Camaro OBD1-stock pcm (have no interest in swapping PCM's right now)
383 lt1
80lb High Imp. Injectors
Granateli MAF
58mm Throttlebody
Stock ported intake manifold.
Aeromotive FPR (dunno model sorry, its on car currently)
Duel intank walbro 255lth pumps, one on 4psi hobbs switch.
2.5bar map sensor from (link)

Planned boost is 15 up to 20psi.

Iam trying to understand this MAF vs speed density stuff. Will it be able to be tuned using the MAF like my N/A engine is, or is there some other voodoo stuff that has to go on for the stock pcm to work with this amount of boost?

I like the idea of it being able to read stuff and correct fueling etc with the MAF, but have heard it will quickly get maxed out and be worthless?

Is there anything else iam forgetting? Can I just call up a mailorder tune place like pcmforless and get a base tune to get it to the dyno?

Thanks in advance for any replies!

David94TA

I'm no expert by any means, but I'll throw in my 2 cents worth. Sounds like you are pretty much good to go with your build. If you aren't doing the tuning yourself, your suggestion of getting a mail order tune and then taking it to the dyno makes good sense.

If you are wanting to do some tuning yourself, you need to get a wideband O2 sensor with logging capability and software like LT1 Edit or Tunerpro.

One question though, are you trying to use the 2.5 bar map sensor work with your stock PCM? If you are, then that is a whole different ball game.

You are correct in that the MAF will max out, but a competent tuner will know how to handle that. FYI, I haven't seen any positive comments on the Granatelli MAF--can't remember what the problems are, I would have to look it up.

Hope this helps some. I'm doing some tuning on mine right now with an Innovate LM1 wideband and LT1 Edit. Like I said, I'm no expert but I'll be glad to share what I know or at least point you in the right direction. Just PM me.

Injuneer

Assuming you are using an Aeromotive LT1 AFPR, you might want to do some more reading. There are numerous reports of that item failing.

The Granatelli is also a mistake. It is intentionally miscalibrated at very high G/SEC rates to read lower than actual flow. That leans the top end out in a stock tuned system, and leaning out the target A/F ratio in power enrichment (PE) mode is generally worth 15HP or so. (PCM still uses the MAF reading in PE mode - it just changes the target A/F ratio based on programmed tables). Same gain could have been had by a correct tune in the PE tables. But I don't think you should use an MAF sensor the is intentionally miscalibrated. It offers no advantage over the stocker.

coolraptor

David, Iam planning on taking it to be tuned. I have too much $$ in this thing to risk trying it myself as I have no real tuning experience.

I was planning on using the 2.5bar sensor with the stock pcm, but I see what your saying and will go with whatever the tuner decides. When I bought it, I was not sure if it would work with the stock pcm or not.

I also have a innovate wideband gauge/kit that will be getting installed before any tuning goes on, mainly so I can keep an eye on it while driving or at the track.

Injuneer- Funny you should mention the fpr failing, it did a few years back lol some o-rings decided to give up and soak my engine in fuel. Luckily no fire, and since we put new o-rings in it has worked OK for the past 5-6 years.
Iam assuming thats the main fail point on those? I,too, have read on them failing and alot of the times it seems to be an o-ring issue.

The granatelli MAF has also been on the car for a few year and the pcm was tuned with it. I do have a stock MAF (descreened though) that I can put back on before tuning if you think it would be beneficial?

Thanks for the replies! Iam pretty clueless about tuning stuff and appreciate all the help!

Sorry it took so long to write back, I cant seem to figure out how to set it up to notify me of new replies