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MG MGB GT V8 Factory Originals Technical - Turbos for aluminum V8's

Any comments?

I wish , I wish

Looking at their components, I don't personally feel the kit is worth the money. If you wanted to go turbo, be it single or twin(both would work almost as well for our purposes) I would probably do what a lot of the 5.0 boys do and flip the exhaust manifolds and run the pipes from there. If you wanted to drop that much cash for custom made manifolds, I can give you the names of people well capable at a far less amount than that. I really don't see any way to mount any turbo system in a MG with a V8, either in front of the motor or to either side.

For turbos, a single T4 would probably work, depending on what you are looking for, or maybe something like a Holset HX40. For Twins, a pair of T3's off a turboford would probably work well. If you are worried about lag, get the .48 housings, but most probably the .63 would work out better. With either opition, you would need to do the math and look at the turbo maps to determine the proper turbo for your application.

For fuel systems, I would either switch over the the Ford EEC IV system and purchase an aftermarket tuner(like Jim did), or go to a stand alone system. Whlie there are a few blow through systems that seem to do OK, I would personally go EFI. You would also need a good fuel pump to supply enough fuel, along with a good boost referenced fuel pressure regulator.

Now for intercooler...good luck getting anything in the front of a MG. I have seen a starion cooler mounted down low in front without cutting it apart, but anything else would probably require a custom unit.

I am sure I left a bunch out, but it is late and my poor little mind is getting sluggish. If I left anything out, just ask and I will try to give you an answer or direct you in the proper direction!

G.P. Copes

One of the TO4B's would likely work very well. I think the 46 series maybe.

There is an entire board devoted to blow-thru carbs. They really know thier stuff. the big issue would be the bonnet for the carb and getting it under the hood.

Heh NEVER enough power!! heh

Larry Embrey

I had the Jetfire turbo on my car before going to the Eaton. It required a wide hood scoop but only about 2-1/4" tall and was no problem to see over. I used the 2" SU from some Jag 4 cylinder with an enlarged main jet and custom needle, and fabricated 8-4-1 headers with the collector at the turbo inlet. On an engine with about 6:1 compression (Olds 2bbl with 8:1 Buick pistons built by a buddy against my advice) it produced 7psi boost without reworking the waste gate spring and performance was quite good, though nothing like what I'm seeing now. I ran a low 15 second quarter on the only day I took it to the strip (a better driver would have improved that considerably) and though it did have a little lag it was tolerable most of the time. (Most INtolerable when going past a car around a curve on a slick freeway. Ouch!)

Eventually the shaft bearing got sloppy enough to let the impeller drag against the housing and off it came, to be replaced by a rootes type blower. I still have the complete setup though if anyone is interested in playing with it.

Jim Blackwood

Jim, you have mentioned twice in the last couple of weeks that you used a 2" SU from a Jag 4 cylinder. Was it some pre-war SS car or something? I have never seena 4 cylinder Jag.

I could be mistaken about that. I pulled it off an engine sitting up at "Auto Jumble" in Ohio several years ago during an outing at Mid-Ohio race track, never saw the car. IIRC it had Jaguar on the valvecover or elsewhere on the engine and was a 4 cylinder with dual carbs. I thought it was somewhat odd as I was under the impression that all Jags had either 6 or 12 cylinder engines, and I did not recognize the car model I was told it came out of so I just assumed maybe it was some gray market car or another, or perhaps some downscale sedan I'd never heard of. The engine didn't appear to be ancient.

Yes, it's a bit of a puzzle, anyone have a clue? Or... maybe it was a 6...

Jim Blackwood

Well..that is the start of a decent system (although I have no idea about the the specs for the turbine side or compressor side of the IHIs. Are they sleeved or ball bearing turbos?

What is missing from that kit??
Are those turbos oil and water cooled? If so, where is the plumbing for the lines? Feeds and returns.
Just Oil cooled...??? I guess that is OK, but I like Oil/water better?

Oil spray jets for the underside of the pistons and maybe stronger lower compression pistons.

Downpipes or at least the outlet flanges for the outlet side of the turbos? Stainless of heavy weld-el pipe, support brackets, heat shields.

Antisurge valve or Blow Off (to prevent compressor surge when the throttle closes suddenly)?

Intercooler plumbing, Air inlet plumbing. Silicone reinforced hose connectors and an assortment of T clamps

For serious boost 10 - 15 psi, You will need An ECU or piggyback components to add fuel and pull timing on boost. Also larger injectors to meet the additional fuelling requirements. For ECUs - A Haltech E6K is a bargain new at about $1,000 with air and water temp sensors. You will still need a linear TPS (throttle position sensor) to really dial in idle control and a Two (14.7 max) or three bar (29.4 psi) map sensor to measure boost and send the appropriate signal back to the Haltech. Yes there is better- say a Tec III - but then you're up to real $$$ (say 2,500). A programmable ECU and upsized injectors (or additional injectors) is a more tunable setup for a high performance system.

If you are sticking with low boost, maybe an AFPR (adjustable fuel pressure regulator- gets a boost signal from the manifold and adjusts fuel pressure upward on boost- no boost 45-50 psi fuel pressure but 100 psi at 8-10lbs boost) and also a Mallory or Bipes control for the timing to pull timing on boost to prevent detonation. Not perfect, but pretty good.

Take offs on that air box for a boost guage, wastgate signal, MAP signal and Blow Off Valve control.

As far as guages, I'd want at minimum, Boost guage and 2 manifold temperature sensors, and A/F meter.
For tuning the ECU maps, a wideband O2 sensor would be nice.

Boost control solenoid or cheapo but highly effective brass bleed valve.

twin 2.5 exhaust system with crossover and turbo mufflers (remember turbos muffle the sound quite a bit themselves)

But other than that it looks like a complete system (Bwahahahahahahah).

Rather than spend money for this system, spend less than $20 and buy Corky Bell's Maximum Boost. The best investment you will ever make if you are considering a turbo system.

P.S. I'm actually in the middle of a cheapo turbo build up for my 90 miata using a Garrett T25 water/oil turbo off a late model turbo eclipse, weld els to build a manifold, two WRX Intercooler cores welded together, an early turbo eclipse blow off valve, haltech E6K and 450 cc eclipse injectors. All for less than $2,000 (so far)with a very doable RWHP target of about 200 hp. Two new T3's (if that's your preference could be had for about $1,000. After that, the air don't care if you are using new or used IC cores.
Brian C

Sounds to me like you guys like expensive horsepower. ;-)

I guess you have to figure in the gee-whiz factor too. But don't forget the blow-up factor while you're at it. :-o Of course I can't say much but other than sweat equity you would be amazed at how little money I have in my buggy. Bought the engine with a parts car around it for $1500 or $1200 not sure which and it was a brand new rebuild from a local racing shop with a good reputation. The blower was another $1100 brand new, then figure in a few hundred here and there for things like junkyard fuel injection parts, and about $600 for the tweecer add on. Any way you do the math that's less than $5000 including the engine, probably closer to $4000. It helps to be able to make some parts of course but don't assume I had a full scale machine shop at my disposal because that wouldn't be true. I had the use of a small ($1200 at harbour freight) bench mill and a few other common tools. The key is ingenuity.

But for the money, the SBF is a very good way to go. Pick up a good runner for under a grand and you're off to the races.

Jim Blackwood

heh boost is good!! I have the boost bug badmyself right now, but that is not for the B. She will be just fine NA. the 635 on the other hand could use a nice single or twin system, about 15psi ought to do nicely!!

Larry Embrey


A little off thread, How do you like that bench mill? What can you do with it? what are its limitations? Think it is worth it?

Back on thread: Expensive horsepower!!?? Alright, you can do it cheaper with a good deal of Pick-a -part scrounging and ingenuity. Forget the aftermarket ECU and use a GM box. Go to and download their tuning software and appropriate calibration files for about $200. An eprom burner and a couple of EEPROMS for about $100 more and you are done. Prepare to learn a hell of a lot about lookup tables and ECU function. That is my idea of a good time.

Pressurized carbs-in-a-box are a mystery to me, but that might make the whole thing alot less expensive. I guess you still need variable pressure for the fuel pump - if carb requires 4 psi of fuel, then you need the pressure to be turbo boost pressure plus 4 psi to keep fuel going into the carb. Then a mallory turbo timing box to pull advance on boost?? You would also want a decent mixture meter for tuning (or permanently installed) and a couple of EGTs to keep an eye on exhaust temperature.

At the end of the day, there is no way to do a cheap properly setup turbo system (fuelling, Intercooler, timing control, etc..) without getting a welders tan and cobbling it up yourself. On this path, any new parts you buy should come from Home Depot's plumbing aisle, not a speed shop.

BTW, Jim, that is one wicked beast of a car you've got there. I'm truly awed by the work.


Brian C.
Brain Corriagan

Thanks for the compliments Brian, it was a lot of work but most of it was fun. I see where that machine (Mill/Drill) is on sale for ~800 bucks. It's a fairly capable unit, but if I was in the market for a mill I'd look for a second hand Bridgeport instead. Even with the oldest sloppiest one you might find the capabilities will be much greater, and for $1000-$1500 you can find some really decent machines. I have a Moog Bridgeport NC which I am retrofitting for CNC (at a very slow pace) and the machine was actually *given* to me for hauling it off. It has chromed ways and no discernable wear anywhere. I expect to have around $3000 in it by the time I'm finished. Don't be put off by the 3 phase motor, there are cheap ways to deal with that too. Possibly the best is a variable frequency drive and you can pick those up on ebay for around $100. Or, a larger 3 phase motor can be used to generate the 3rd phase from residential 220. Either way it makes the standard mill very attractive, as long as you have the shop space for it.

I used a pull through carb on my turbo setup so fuel pressure was never an issue. The stock Jetfire had water cooling of the housing and also a liquid injection system which I did not use. Personally I do not like a turbo for this type of car though. The potential is just too great for breaking the rear end loose at the wrong time. I am an experienced driver and have a great deal of seat time in cars where the wheels were going in directions other than those they were designed for, and I am rarely caught unprepared by the back end stepping out, but this car with the turbo engine on two occasions put me so sideways that all I could do was watch while I pushed other drivers into the wall on the freeway. That's totally unacceptable, and though at first I thought it a fluke after the second time I had to accept the fact that this was a bad combination. The problem is twofold. First the turbo lag and subsequent rapid accelleration puts you at the edge of adhesion, does it very suddenly, and makes it difficult to predict exactly when it will happen. Secondly, the car's design and suspension being optimized for handling rather than accelleration, it is easy to break adhesion with large sudden applications of power, particularly if any side forces exist, which will immediately compound the whole situation. And the car is made specifically for generating such side forces by being capable of great maneuverability. So you have the situation where the car can easily be at the limit of adhesion all on the strength of it's handling ability, then you throw in a sudden and somewhat unpredictable application of considerable power and I think you can see the potential for disaster. Not that you can't build a safe high powered turbo MGB, but for my money the supercharger is a smoother and therefore better option. Or the blue oval of course.

Jim Blackwood

This thread was discussed between 23/08/2003 and 25/08/2003

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