85 mm MAF upgrade for VY SS?

I'm looking at installing a bigger MAF on my currently stock, but later 220° cammed VY SS Commodore M6. I have a set of 4:1 headers and a set of 243 heads to go on, and I'd rather have an initial play with a bigger MAF than go MAFless for the street.

I'm thinking of running the 85mm MAF out of the Corvette and Escalade, etc, the GM 25318411, like this one:

http://i18.ebayimg.com/04/i/08/c9/e2/c4_2.JPG

It appears that this can be adapted to my VY harness with one of these 3 pin to 5 pin adapters from Caspers:

https://www.casperselectronics.com/M...ges/108100.jpg.

I think VCM Suite in Australia promote a similar mod, using the VZ Commodore MAF. Is it feasible with EFILive by adjusting the MAF calibration? I've searched and can't find anything specific to this swap.

John

Hi John,

I ran with an 85mm MAF for a while years ago (on a 2000 VTII), I think it 'felt' different to drive for sure (for the better).
It is simply a matter of copying the 85mm MAF table from one of the US vehicles that used them.

But, keep this in mind. You will need a new MAF pipe, plus the cost of the 85mm MAF and harness adaptor. OR, for Mafless, just the pipe. Remember, MAFless was good enough for HSV to sell as a $90,000 street car.

Maybe a shop with a dyno might chime in here to give you some numbers on a MAFless v's 85mm MAF with a cam like yours.

Cheers,
Ross

I vote save your money for a fast90/90 setup and go mafless now.
Have a look at the GTS tune as GMPX says.
If you want to play stock, play mafless stock.
No point throwing your money away on a new maf when you will only be throwing it away a few days after you get your heads and cam.

PS: What cam are you getting? Go for 0.580 lift. You will need new valve springs in any case

Quote:

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Originally Posted by GMPX

...But, keep this in mind. You will need a new MAF pipe, plus the cost of the 85mm MAF and harness adaptor. OR, for Mafless, just the pipe. Remember, MAFless was good enough for HSV to sell as a $90,000 street car.

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Thanks very much for the quick response Ross. I'm glad to hear from you that this is easily do-able.

I understand what you're saying about the HSV SD tune, but I'd like to do this as a learning exercise, and I've bought a MAF pipe and 2-holed/K&N air box for $120 and after reading what you've posted, I've just pressed the Ebay button on a MAF for USD62 delivered, so it's not a big cost. I'll do a MAF/MAFless comparison on a mate's dyno and post the results.

Quote:

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Originally Posted by ringram

... What cam are you getting? Go for 0.580 lift. You will need new valve springs in any case.

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I don't know what cam yet, but I'm thinking about sticking to a max lift of 0.570" because that is apparently the limit for the yellow springs in the 405hp 243 heads I have. A local cam grinder has a 223/223/0.565" with 112 or 114 LSA that looks interesting, and it doesn't have XER type aggressive ramps so the yellow springs should be okay. I'm in the recycling industry, and I plan to put this together out of as many recycled parts as I can ;).

Thanks again for the advice blokes - I'd be glad of any other suggestions about this combination.

John

Quote:

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Originally Posted by ringram

I vote save your money for a fast90/90 setup

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Do they make much difference on a stock motor?

Cheers

Quote:

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Originally Posted by ringram

I vote save your money for a fast90/90 setup and go mafless now.

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A little birdie told me there is a nice manifold coming this year that is a VERY nice alternative to that one with some very impressive back to back dyno numbers.....

JohnL, when it comes to modifying your car, cost is not an issue with you, only the one you have to explain it to ;-)

Cheers,
Ross

Quote:

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Originally Posted by GMPX

JohnL, when it comes to modifying your car, cost is not an issue with you, only the one you have to explain it to ;-)

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You've just touched on another of the excellent reasons to buy recycled parts. Besides the greenhouse gas emissions and resource depletion savings, I can tell her how much I've "saved" on every purchase ;).

Works for me so far...

John

Personally Ebay works for me, then I don't need to deal with the 'expert' behind the GM parts counter telling me it won't work because the 'brain box' will go in to "limps (with an 's') home mode'..........

I try and do things as cost effectively as possible too.
On the fast90 front, Ill have some before and after dyno numbers soon.
But logging with efilive and no other mods I went from a max of 0.86g/cyl to 0.95g/cyl, thats a 9.5% increase in air. Hopefully that relates fairly closely to power.
On a stock engine its probably not worth it, but if you have heads/cam etc its definately worth it. I picked mine up while in the US so saved a bit on costs.

So totally recommended if you have mods.

Some random, rambling comments---

If you have the ability to tune, I can't see any reason to spend money on a MAF. I've been experimenting with my C5, using custom OS3 and 5, running SD in both closed and open loop, and the car runs great either way. I still have the MAF in place because I haven't had the chance to rewire for a separate IAT sensor, so I don't think running SD itself has given me any power increase. I did the conversion as a learning experience in preparation for a cam swap, which I just completed (232/236/114). With the stock cam, drivability is every bit as good in SD as with the MAF.

Keep in mind that these are not true MAF systems-- I call them hybrids because they rely on SD air flow calculations pretty heavily below 4000 rpm (in most cases-- look at B0120). That being the case, the system is constantly comparing calculated to measured air flow and correcting as required.

Ross seems convinced that a MAF isn't good for much besides being a pretty good paper weight, (I think that's a result of the coriolis effect in the Southern Hemisphere and too many years of driving on the wrong side of the road.) which brings up questions about why GM spends money to include an MAF in most vehicles. I think it's primarily to ensure that air/fuel ratios stay within spec across a wide range of operating conditions, and vehicle aging. Auto manufacturers have a whole host of emissions/fuel economy requirements they must meet, and have to guarantee emissions compliance for 8 years and 80,000 miles. Those concerns are only partially relevant when you're monitoring and adjusting engine calibrations.

In my experience, the FAST manifold isn't worth much on stock and lightly modified LS1/LS6 engines. I picked up 8-10 horsepower after considerable tuning on a car with a mild cam, but that's only because we didn't have time to tune with the LS6 manifold in place. A friend of mine picked up an honest 10 horsepower on a highly modified LS6 engine-- that's optimized tuning on LS6 manifold and optimized tuning on FAST manifold. I think larger displacement and/or supercharger/turbo is where the FAST pays off.

For anyone who's interested, I have a brand new 90mm FAST throttle body for sale, and I can get you a pretty good deal on FAST manifolds and Comp Cams camshafts.