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FITECH for the MGB?

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NOHOME P P
O, ON, Canada   CAN
1967 MG MGB GT "Maggie (GT From Hell)"
I am going to be interested in the feedback of this build over on the Sprite forum. If it works on a sprite, I have to think it is the answer for the MGB if people want affordable EFI. Not that the SU wont get the car out of the driveway, but I have seen and experienced the difference between Carb and FITECH muscle cars and the things do make a difference in driveability.



Pete

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ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
That's a good one a EFI body flowing 4 times what an MGB can utilize and who knows how oversized it is on the tiny engine shown.
The things people dowinking smiley



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

Nicecar Avatar
Nicecar Gary (ex "Harv") G
Victoria, BC, Canada   CAN
1980 MG MGB "Red On Red On Red"
Heard this first on "Car Talk" years ago, and then later somewhere else.

So, let's not forget the guy who welded a jet engine onto his car?
Result: Car took off, and he crashed into mountain side.

I love my low compression 18v with ZS. If I have a problem with engine I fix it; otherwise I got 10 million other things to do with my time, like adding a heated coffee mug, (or maybe brushing my teeth).

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converse212 Avatar
converse212 Eric Morgan
Atlanta, GA, USA   USA
1958 MG MGA
1970 MG MGB "Daily Driver"
1970 MG MGB GT "Rusty"
1971 MG MGB GT    & more
My boss has been working on a Fitech install in his 302 MGB...it’s given a fair amount of trouble since it’s been installed.

I’ll be interested to see how that works.



Daily driving a '71 MGB

Resurrecting a '58 MGA

matt167 Matt D
Prattsville, NY, USA   USA
The 2bbl Fitech probably flows around 500 CFM so it's probably 'right' for a 1.8 but a little expensive.

The Weber manifold can be adapted to a GM TBI pretty easy, and something like a 2.8L TBI would be close. Then just Megasquirt and use fuel only. Get it pretty close for ~$600ish

Note, the original Austin Mini/ Mini Cooper was built until 2000 and the A plus engine was fuel injected in the later years. Not sure the difference between the A series and the A plus but I'd bet it would be pretty close even to just get the EFI parts. BMC was poor when the A plus was developed. Does not help the MGB crowd, but 1275 Midgets and Sprites it would.

Gerald O Avatar
Gerald O Gerald O'Docharty
Wake Forest, North Carolina, USA   USA
1978 MG MGB
In reply to # 3888873 by matt167 The 2bbl Fitech probably flows around 500 CFM so it's probably 'right' for a 1.8 but a little expensive...

A 1.8 would pump about 190 CFM at 6000rpm if it had 100% volumetric efficiency -- which no normally aspirated engine does. So even at a very high 80%, a stockish 1.8 B engine won't need any more than about 152 CFM.

edit: forgot to divide by 2 for 4-stroke



Edited 1 time(s). Last edit at 2019-02-09 09:13 PM by Gerald O.

matt167 Matt D
Prattsville, NY, USA   USA
In reply to # 3888899 by Gerald O
In reply to # 3888873 by matt167 The 2bbl Fitech probably flows around 500 CFM so it's probably 'right' for a 1.8 but a little expensive...

A 1.8 would pump about 190 CFM at 6000rpm if it had 100% volumetric efficiency -- which no normally aspirated engine does. So even at a very high 80%, a stockish 1.8 B engine won't need any more than about 152 CFM.

edit: forgot to divide by 2 for 4-stroke

HIF 4's flow 240 CFM each at 25" of water ( ~2 HG ). The Go EFI 2bbl isn't rated at CFM but 2bbl carbs are generally rated at 3 HG and a Holley 2300 2bbl is 500 CFM so good guess. Since the HIF 4 was tested at a lower vac ( 25" vs 40" of water ) the twin HIF would actually have a higher flow rating than the 500 CFM 2bbl if measured the same.

That said, I wouldn't use Fitech. I'd use a Microsquirt and a GM TBI from either a 2.8 V6 or an Iron duke 4cyl.. But nothing beats the sound of HIF-4's wide open

Denis Avatar
Denis Denis Hill
Bearii, Nth Victoria, Australia   AUS
A HIF 44/ HIF6 is rated at around 230 CFM not the HIF 4



68 B roadster, Daffodil yellow, supercharger, Burgess SC head, SC cam, Mikuni HSR 48 carburetor and engine built for supercharging.

73 BGT V8 conversion starting with a bare shell. Built the engine "3.9L Rover" early in 2016 with high comp pistons and a few other nice bits, plus a T5 ford trans. Started on the body late 2016 and complete late 2017, Did all the work myself, mechanical, body. paint etc.
Finished and going well, great to drive and quick. Now has a nice 3.23 LSD.

ohlord Avatar
ohlord Gold Member Rob C
North of Seattle, N.W., USA   USA
1957 Land Rover Series I "EYEYIYI"
1971 MG MGB
1971 MG MGB "Bedouin 2"
At 5500 rpm the demand on each HS4 su carb is about 85cfm a 500 cfm anything isnt right for an MGB
Makes a good joke though



"I'm a long way gone down this wild road I'm on
It's gonna take me where I'm bound
It's a long way around"



"These are the days that must happen to you"

RD2 Radar/ Electronic Warfare Technician
Vietnam 1969-1972

NOHOME P P
O, ON, Canada   CAN
1967 MG MGB GT "Maggie (GT From Hell)"
It is a 2 barrel version of the FITECH, not a 4 barrel.

CFM numbers on a throttle body EFI do not translate directly to those of a carb. EFI does not rely on the vacuum signal to extract fuel from the float bowl and mix it with air, it delivers atomized fuel in response to demand from the engine and calculations from the computer.

As I said, I know from experience that they are much better than a carb for the 302 crowd unless you screw up the install.

Paul755 Paul H
Fairfax, VA, USA   USA
1974 MG MGB MkIII
1979 MG MGB MkIV "Nemesis"
There is a warmed over MGB GT that has a FiTech 2 bbl that replaced a Weber on a Cannon inlet manifold in my local area. I met him last week at a local "Coffee 'n Cars" meet up. He claimed that it ran very well and gave him a sizable bump in performance. He had been through twin SU's and a Weber set up prior to the FiTech. His engine was running 9.5:1 CR with a Piper 270 Cam, worked over head and EDIS-4 ignition system. It certainly idled very nicely.

Gerald O Avatar
Gerald O Gerald O'Docharty
Wake Forest, North Carolina, USA   USA
1978 MG MGB
Lots of misunderstandings in this thread.
First, the CFM flow rate of individual twin carbs on the MG cannot be added to compare with a larger carb or throttle body that is dumping into a plenum type manifold. The two twin carbs are not connected by a shared plenum so only one carb is flowing at any given moment.

Second, the flow rate required by an individual cylinder cannot be 'averaged', or taken as 1/4 that of the entire engine. Its peak flow requirement must be met, which is the same flow rate as the entire engine. So if the engine can pump 150 CFM, then each cylinder also pumps at that rate, but in an interrupted manner. Since only one cylinder is drawing through the carb at a time, a single 150 CFM carb cconnected to a plenum serving all 4 cylinders would, in principle, satisfy the flow needs. However, if each cylinder were only fed by its own separate carb, it would still need 4 carbs of 150 CFM each. In the case of the MGB, with two pairs of siamesed intakes, two 150 CFM carbs are needed. This is of course a simplification, as it does not take into account air velocity and momentum effects of the 'pulsed' or interrupted flow, which tends to raise the nominal flow spec required from the carb. In short, the twin HS4 or HIF4 carbs are the right size.

pinkyponk Avatar
pinkyponk Gold Member Adrian Page
Berwick, NS, Canada   CAN
How would fuel injection give a bump in performance? I can see it might drive better during warmup... but beyond that I see no reason how it could produce more power... unless his carbs were too small or not tuned correctly.

Adrian



Home built Eaton M62 Supercharger with 7.6psi boost, 8:1 compression, custom "supercharger" cam from Schneider Cams, Mikuni HSR48 Carburetor, cold air intake, ported head, matched manifolds, CB Performance computerized ignition, Fidanza 9 pound flywheel, Maxspeeding rods with Teflon wrist pin buttons.

B-racer Avatar
B-racer Jeff Schlemmer
Shakopee, MN, USA   USA
1950 Willys Jeep Pickup "Ratrod"
1971 MG MGB ~ For Sale ! ~
2014 Dodge Charger
The nay-sayers never fail to surprise.
EFI throttle body sizing does NOT work like sizing a carb. You need at least 30% more airflow capability than the engine can process. A well ported MGB head should be able to handle a 475 cfm throttle body, possibly considerably more. Dual-Weber crossflow heads flow far, far more. $799 is expensive for fuel injection? Are you kidding???

As for my experience, the 302 problem mentioned above has more to do with faulty wiring, O2 placement, and exhaust leaks than the FiTech's fault. Hard starting and failure to self-tune are usually voltage issues caused by inadequate power flow from the battery and the ignition fed wires.

While its an ultra-simple software with crude tuning capabilities, it works astoundingly well after its been in place for a couple years use since the self-tuning continues to learn, albeit slowly. Most folks will never get a carb to run as well as this system. Most folks could never get a Megasquirt to run half as well.

By the way, at 4500 rpm, SU HS4s run out of steam. A typical MGB head flows 125 cfm, 140+ with mild porting, and a lot more is possible if you spend enough time or money. Given the wild pulses that can develop with the 1-3-4-2 firing order where you're pairing intake runner pulses, 2-1, 3-4, a more open plenum aka a larger throttle body can help with overall performance. Then take into effect the progressive throttle application from the FiTech's re-clocked Holley-style throttle throttle and a steeper throttle plate angle, low end performance is enhanced.

This will always be the aluminum flywheel argument. Those who haven't tried it hate it, while those who have absolutely love it. In the mean time, folks who don't know will spread false information because they read it on the internet.



jeff@advanceddistributors.com

Paul755 Paul H
Fairfax, VA, USA   USA
1974 MG MGB MkIII
1979 MG MGB MkIV "Nemesis"
I am just passing on what the owner reported. As he is an actual real live driver of a FiTech modified MGB and did seem to be mechanically well versed in MGB engines and perfomance, I will take his word for it.

In reply to # 3889042 by pinkyponk How would fuel injection give a bump in performance? I can see it might drive better during warmup... but beyond that I see no reason how it could produce more power... unless his carbs were too small or not tuned correctly.

Adrian

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