F3 cam in TBI?

[TD3]

I've seen a few things on here about it, but not a lot of information. Mostly just curiosities and rumors. Anyone have anymore information on this cam or any other good cams for the TBI engines?

[The Pope]

the MP NA cams had more duration than lift, because the ports are too small and stall on the flow bench.

FI cams needs good engine vac and have to be cut differently, normally means less lobe sepperation angle.

MP cams had .460" lift, many anyway.

The F3 cam has a little more lift, for the head flow. It has a lot more duration to raise the RPM range of the engine. And it has wider LSA for more engine vac at idle for the FI to work right. So the cam should work very well.

Auto Part Number 500-1 From Holley | StreetPerformance.com


In order to get more RPM, and more HP you need to have more CFM. Holley has a 500-1 part number for there single injector TBI. It is time to try it and raise the fuel pressure.

http://www.carburetion.com/calc.asp

mildly built 153 CID (2.5L) engine running under 7,000 RPM, 6,500-7,000 with the right header and cam. Requires almost 300 CFM, so even a stock engine wants 250 CFM. The stock TBI is closer to 175-200 CFM being generous.

So theory as people haven't tried modding a TBI, on paper it looks good though.

[Vigo]

I agree with Pope in the sense that the tbi itself is much more of a bottleneck than the stock cam.

[The Pope]

much like building a V8. Our TBI people remind me of these stock class guys trying to make a 318 2 barrel run without going to a 4 barrel lol. Big cams and ported heads, etc aren't going to work lol.

Actually the TBI cam is not small. V8s and the Ford 2.3, etc only wish they had a cam so big lol. The Shelby dak has a .385" lift cam lol, going to a .450" was MASSIVE.

Adding a Weber to a 2.2 is like adding nitrous. Yet you have to look at why. The 2.2 likes air pure and simple is restricted on the intake side with every engine but a T3 lol.

One of the best running NA engines out there I've seen was a guy that ran a blower B&M intake with a 390 Holley carb and the 280M cam. Side drafts are better but a lot harder to tune. That 4 barrel setup made for a reliable every week end road course car.

You can get the Holley, reman pretty cheap without sensors and an injector, the core TB unit. You need to run the 2.2 injector and sensors anyway so getting a core isn't bad. You need to use a wide band to find AF for WOT and you need the OTC scanner to see if the 02 is adding or removing fuel. Then adjust AF to compinsate the best you can.

Being that the Chevy based TBI units are shorter than Dodge versions you could add a box under it, a 2" tall spacer / adapter for more plenum volume too. From many directions it looks to be a good idea, we just need a TBI loyal to try it lol

[Vigo]

Id kind of like to be tinkering with a tbi/5spd again but i dont have one to mess with and i wouldnt spend more than $300 to get one.. hehe

[TD3]

I was thinking of converting to MPI, and batch firing the injectors. Then, adding a good cam and headers. Maybe do some head work, or just get a JY turbo head depending where I'm sitting after the cam.

[TD3]

Does anyone make any cals for the TBI's? I saw a few times that Shel-Game was toying around with it. If I could get a plug and play system over going MS, I would. It seems to me that the TBI's have INCREDIBLY restrictive programming, and is one of the biggest restrictions besides the intake.

[Metalheadxp]

Tell you what. I have an '88 TBI Omni. Once I get it back on the road, I'd be willing to try this stuff out. I lightly ported and polished the head myself, and added MSD ignition parts and I did notice a gain in throttle response and acceleration, but have been wondering what options I have with the TBI. I tried increaseing the fuel pressure once with an adjustable regulator but that didn't work out. I am also going to build a header using an FWD flange I got a while back. I didn't know the TBi unit was GM based till I saw this article!

[Vigo]

If you do the MPI conversion, spend the extra money and do it with a 2pc intake vs a 1pc. The 2pc is, objectively, a pretty good OEM intake manifold by most standards, while the 1pc is universally just crap regardless of context.

The only reason cars with 1pc intakes make more than 110hp is because they have turbos. Now keep in mind, 110 is a totally crappy number for an MPI 2.2 or 2.5L.

The 1pc is so bad i wouldnt bother to swap one on. Either upgrade the TBI unit or go with the 2pc.

[TD3]

I was thinking a ported 2 piece, actually. They aren't that expensive, and I could get them from one of the vendors around here. Then the 52mm TB upgrade and I wouldn't even have to worry about air flow on the intake side. I think that set up would DEFINITELY take advantage of a deep breathing cam with a good exhaust. I think the stock turbo injectors should be good enough for the fuel, I don't really think I would need to upgrade those. Also, turns out the High Performance class I'm taking over the winter semester in college uses MS. So, I may be looking at that after I get past the learning curve. Would make for one helluva N/A motor.

[Metalheadxp]

Holley's website says that regulator is for 5.0L Mustangs.

[TD3]

I don't think The Pope said it was direct bolt on, but in fact that it would work if you made an adapter plate and transferred the hardware.

[The Pope]

Holley makes carbs and TBIs for a few companys, not just Mopar. Yeah this one is different and made for the Chevy 2.8. It also was part of a Holley projection kit for Jeeps.You can find them, without sensors online fairly cheap. Then add your sensors, which ever is needed for the Dodge computer. Stuff is pretty close, Dodge and Chevy. We run the GM 3 bar map and GN 3.8 adjustible regulator on the 2 piece.

Lot better idea than trying to mod the Dodge unit, too thin and it'll just go through boring it. There is running the 3.9 2 barrel but then you have 2 injectors. So best cross over plan.

[mrglenn]

This is good information to know about the holley unit after all the one that comes on the car is made by holley. Pope you the Man.I wonder what the stock one on a 80s GM car flows ?

[The Pope]

though bigger than ours not 300 CFM. People say it adds 15-20 HP to a 2.8 Chevy though lol. Got to help a 2.5 Dodge too.

being a pick n pull item it can't cost much to get a stock Chevy unit and check it out. I've heard people mod the Chevy one to get there but haven't checked on it