Ac Delco Maf
Thread Starter
Intermediate
Joined: Aug 2006
Posts: 40
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Ac Delco Maf
Can anyone tell me the flow rate of a new AC Delco MAF? I am running a 88 l98 stock bottom, ZZ4 heads, Super Ram, Transgo Shift kit, 3.73 gears, 52 MM BBK throttle body, 160 thermostat, fastchip, 24 lb injectors, catbacks, slp cold air induction. Is the AC Delco OK for this or should I buy a new Granetelli? The Granetelli is advertised to flow at 47% better than stock. Stock was a Bosch that flow at 518 CFM with the screens on. I think the AC Delco flows at about 750 CFM but that is a guess. The Granetteli may flow better but do I need it with my low HP estimated at about 300.
Melting Slicks
Joined: Aug 2003
Posts: 3,403
Likes: 398
From: Lakeville MI
I believe the granatelli is a re-badged adjustable Micro-Tech MAF, You may want to see my post on the calibration issues with the Non-adjustable Mico-Tech MAF.
http://forums.corvetteforum.com/show....php?t=1418881
I can only assume that the adjustable version will have similar issues, but perhaps could be compensated via the adjustment screw. I would be wary as the output is not exactly linear.
There maybe some flow benefits as there is only 1 screen and a flat circuit board, compared with the dual screen/hot wire set up. I would guess it would be similar flowing to a descreened stock MAF.
If your existing MAF is working fine, I wouldn't mess with it.
From tpis flow data
Stock MAF 529 cfm
Screens out 711 cfm
Fully modified 750 cfm
I ran with my screens removed for years before my stock bosch MAF eventually failed. My calibration comparison above is relative to my descreened stock Bosch MAF.
http://forums.corvetteforum.com/show....php?t=1418881
I can only assume that the adjustable version will have similar issues, but perhaps could be compensated via the adjustment screw. I would be wary as the output is not exactly linear.
There maybe some flow benefits as there is only 1 screen and a flat circuit board, compared with the dual screen/hot wire set up. I would guess it would be similar flowing to a descreened stock MAF.
If your existing MAF is working fine, I wouldn't mess with it.
From tpis flow data
Stock MAF 529 cfm
Screens out 711 cfm
Fully modified 750 cfm
I ran with my screens removed for years before my stock bosch MAF eventually failed. My calibration comparison above is relative to my descreened stock Bosch MAF.
Thread Starter
Intermediate
Joined: Aug 2006
Posts: 40
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Thanks Tequilaboy, I like your vette. Your times are good. How do you like the 1.5 rr's? Will they pass a Cali smog? Do you recommend them for my car? I am running a super ram with slp cold air, 24 lb injectors, ZZ4 heads, rebuilt stock bottom, magnaflow catbacks, Trango shift kit. I have only race once. It was a bracket race for Corvettes only. It was hot and I was running 2.73 gears. My best time was 14.3 and 98 MPH. I had street tires. I now have 3.73 gears and a rebuilt diff. I would like to get around 13.5. Maybe I'm there already? I have been thinking about 1.5 rollers. It's a cheap and easy bolt on but will it affect my smog, will it give me better times?
Team Owner
Joined: Sep 2001
Posts: 62,161
Likes: 1,733
From: Athens AL
C7 of the Year - Unmodified Finalist 2021
C4 of Year Finalist (performance mods) 2019
ZZ4 heads are no different than what came on your 88 from the factory. 1.6rr will pass smog fine, you just have to tune the engine properly.
What you need is a better cam to go with the SR, and have those heads ported. Then have a chip done and it can pass smog. Accel 219 is what you need, it can be tuned to pass.
Granatelli is crap, I wouldnt have it. But the MAF is not your problem.
3.73s are also too much for the engine as it is.
What you need is a better cam to go with the SR, and have those heads ported. Then have a chip done and it can pass smog. Accel 219 is what you need, it can be tuned to pass.
Granatelli is crap, I wouldnt have it. But the MAF is not your problem.
3.73s are also too much for the engine as it is.
Last edited by vader86; Aug 26, 2006 at 12:03 PM.
Melting Slicks
Joined: Aug 2003
Posts: 3,403
Likes: 398
From: Lakeville MI
With ZZ4 heads, you should already have LT4 valvesprings.
If this is the case, 1.6 rockers are probably the better option as they're said to be worth a little extra horsepower over 1.5s, maybe 3-5 hp difference.
If you get self-aligning rockers, you can save a few bucks as you won't be needing new hardened pushrods and hardened guideplates required for non self-aligning rockers.
I installed 1.5s a long time ago and at the time, I didn't want to mess with possible valve spring or retainer to guide or seal clearace issues with the 1.6s, so 1.5s were the better choice for me.
Is the 10-15 Hp gain worth the cost of rockers? I think it is.
Note: If you go with 1.6s, this will limit your camshaft choices if you wish to retain the LT4 springs (0.525 lift maximum).
If you plan on keeping the LT4 spings I would go with 1.5s which would still permit use of the popular bigger cams like the 219, Comp 503, GM 846 etc.
Otherwise, the hotcam or Comp 305 would be about the limit of the existing springs with 1.6s.
Sorry, I don't have any experience regarding what mods will pass California emissions, but with the proper tune, I would think that any of the cams discussed here could pass with some ignition retard.
If this is the case, 1.6 rockers are probably the better option as they're said to be worth a little extra horsepower over 1.5s, maybe 3-5 hp difference.
If you get self-aligning rockers, you can save a few bucks as you won't be needing new hardened pushrods and hardened guideplates required for non self-aligning rockers.
I installed 1.5s a long time ago and at the time, I didn't want to mess with possible valve spring or retainer to guide or seal clearace issues with the 1.6s, so 1.5s were the better choice for me.
Is the 10-15 Hp gain worth the cost of rockers? I think it is.
Note: If you go with 1.6s, this will limit your camshaft choices if you wish to retain the LT4 springs (0.525 lift maximum).
If you plan on keeping the LT4 spings I would go with 1.5s which would still permit use of the popular bigger cams like the 219, Comp 503, GM 846 etc.
Otherwise, the hotcam or Comp 305 would be about the limit of the existing springs with 1.6s.
Sorry, I don't have any experience regarding what mods will pass California emissions, but with the proper tune, I would think that any of the cams discussed here could pass with some ignition retard.
