Welcome to our Site for MG, Triumph and Austin-Healey Car Information.
MG MGB GT V8 Factory Originals Technical - MGA LS1
|Has anyone done any research or measurements on dropping an LS1 engine and 6-speed into an MGA? I was going to build a 300" Rover/Buick stroker motor for my (very slowly evolving) MGA V8 project. Then I realized that to support 300" I would either have to use either Wildcat heads (about $4000+ when all set up) or blow/turbo the engine. Then I was looking at an LS1 engine at Spring Carlisle and it looked pretty compact, its an aluminum engine and puts out 400+ HP in mild tune. HMMMMMMMMMMMMMM! There was a complete '94 Corvette rear suspension/rear end there, in pretty good shape, for $400. Anyone know if one of these could be narrowed and still work correctly?|
|I haven't seen much on Chevy V8s swapped into MGs of any type. The rear mound distributor seems to be a problem for most swaps, but IIRC the LS1 is a crank triggered engine with individual coils so that wouldn't be a problem. I've seen a couple of six speed transmissions out of the cars and they are positively huge compared to the T5. It would take a large chunk of your interior room for the trans tunnel with one of these. The later model Corvette rear suspensions used aluminum carriers and control arms, not easy to narrow, so you would probably have to fabricate steel replacements. Lots of choices in independent rear suspensions available in the street rod community, check out some of those on the web, I think you'll find a better IRS for your application. I've only seen one A V8 in person and it used the Buick/Rover engine. Really fits well, but even then a lot of mods to the goal post assembly. http://www.themgdoc.com/mgav8.htm will link you to his website. |
By the way, no MGA V8 experience, but I'm building an inline 6 powered A and have a V6 Midget, so not unfamilair to swaps.
| The T5 5 speed is large compared to a MGA gearbox. The T56 6 speed is large compared to the T5. The MGA box 'just' fits. I think this would require removal of leg and seat room, but no more then an automatic would take.|
Bill S may know how well the T5 fits into an MGA for some ideas.. Maybe he will chime in soon?
I know you have quite a bit ahead of you if you choose that motor. I dont think the structure of a stock MGA will take that kind of power safely and you will need to rearrange and resupport the bay.
You will need to do a substancial amount of work with the rear end as well to get that power usefully to the ground!
|BMC Brian McCullough|
Remember the 302 Ford powered MGA at the 1st Townsend V8 Meet? Yeah, the one that was widened 5-6". There ya go!
Not sure why such a light & powerful combo needs 6 gears, though.
My Dad's Miata has a 6 speed. I told him it needs a gear indicator light to keep up with which gear the car is in!
|Did I hear my name mentioned?|
The T5 fits the MGA quite well. We didn't need to modify the left side of the tunnel at all (well, we did create a couple of small bulges for the speed sensor and reverse light plugs, bu the tunnel still bolts to the same place and doesn't reduce foot room).
The top needs a bit of work to clear nicely, and the passenger side we moved over a little bit, but nothing serious.
The fitting of the V6 and T5 require removal of the round crossmember under the transmission area completely and the reduction of the depth of the front crossmember (which we braced to replace strength afterward).
Installing a V8 normally requires cutting up the only other significant transverse frame element - the square tube at the rear of the engine at the top, simply because of engine length.
I would not be happy about that unless I could replace the one under the trans (difficult to do this and have ground clearance) or properly add another new crossbrace above. Not impossible, but requires some thought and design work.
Go for a GM V6 instead and if you want power, use the alloy head engine and turbo it to get your 300 BHP. Frankly, 400 is a bit over the top in a 2000 pound car, IMHO.
Why not get a small diameter multi-disc clutch setup? That way you get a lot more room in the bellhousing area that you can use for a tubular transverse frame member. Just a thought, I haven't had the chance to look and see how practical the suggestion is, but it seems there might be room there for about a 3" diameter round tube and tying that to the frame rails would add a great deal of torsional stiffness. I know the multi-disc units have become a lot more common and it should be pretty easy to pick up one for that engine. There's a Tilton 3 disc unit on ebay right now at ~$80 and the flywheel must not be much over 8" diameter. Surely that would give you a lot more flexibility in your layout.
|Thanks for the comments guys. Insofar as using the T-56, I would much prefer to use the smaller T-5. However, the T-5 will not take over 300HP and remain reliable. Most importantly though is the bellhousing. The LS1 did was not offered with any other manual trans other than the T-56 and the bellhousing is unique to the 6-speed. Even if the T-5 would handle the torque, building a bellhousing to fit the LS1 would be a real project!!|
After playing with cars for many years, I would, just once, have to face the "problem" of too much horsepower!!!!!!! (or sex!)
|About the horsepower capability, see http://www.fordmuscle.com/archives/2005/12/T5Rebuild/index.php .|
How hard are you going to thrash this thing, anyhow?
|Kurt, a question about the LS1. Is the block bellhousing pattern the same as other small block Chevys? If so then a bellhousing for a T-5 wouldn't be hard to find. I realize that the transmission mounting pattern is different for the T-56 and the T-5.|
From my limited esperience of a twin cam you could not get three hundred horses on a MGA - talk to one of the Gammons family (B&G in Baldock) about their experience of widening one in order to deal with extra power. It will answer some of the points raised here about volume.
Roger - not yet ready to meet my maker.
|Forget hp Think torque!|
I own a 98 LS1 Camaro 3:42 gear ratio and auto trans.
It's a total animal, the body flexes hard during hard take offs, it needs frame extensions etc (wife's car)
I also help with a 99 drag Camaro with a LS7 crate engine, the torque is phenomenal, broke the stock driver seat, not a fun time for the driver.
An LS1 in a MGA would be purely for show and tell and not for real driving, unless....it has a tube frame etc.and then it would be scary to drive due to the short wheel base and narrow track.
Thanks again for your opinions.
Wayne: I would like to do the Silver State Classic where they shut down 100 miles of Nevada highway. You enter a class, for instance 140 mph, and drive the 100 miles targeting an average speed meeting but not exceeding the 140. Some sections are slowed, some faster.
Bill: Bellhousing pattern is different from the previous small blocks.
Mark Barnhart, an automotive aerodynamics consultant who has built a couple of MGA V8's and helped with an MGA which runs at Bonneville, figures an MGA need 400 hp to maintain 140 mph. (My daughter is grown and the will is filled out)
|Wow Kurt, I've seen video of the Silver State Classic. You would definitely need a full roll cage, so chassis stiffness shouldn't be a problem. Might as well shoe horn in a big block, the horsepower wouldn't be any problem with around 500 cubic inches. You definitely extend the meaning of "Safety Fast".|
|"I would much prefer to use the smaller T-5. However, the T-5 will not take over 300HP and remain reliable."|
T-5 Tremec TKO500 & TKO600 handle 500 & 600 ft/lbs of torque, respectively.
We still need to find you a bellhousing.
|> Then I was looking at an LS1 engine at Spring Carlisle and it looked pretty|
> compact, its an aluminum engine and puts out 400+ HP in mild tune
The LS2 is even nicer making 400 net HP in stock form, pulling 30 MPG on the
highway in a 'vette (EPA estimates are 28 MPG highway). The LS7 is even
better at 505 HP but will cost you 2 MPG on the highway (26 MPG EPA highway).
> There was a complete '94 Corvette rear suspension/rear end there
The C5 and C6 'vettes have rear-mounted transaxle version of the T-56.
That would get some weight out over the rear tires where it could do
> However, the T-5 will not take over 300HP and remain reliable. Most
> importantly though is the bellhousing. The LS1 did was not offered with
> any other manual trans other than the T-56 and the bellhousing is unique
> to the 6-speed.
Have they changed the block to bell pattern or is it unique on the
transmission side? Is it one of the SAE spec round bells now?
> T-5 Tremec TKO500 & TKO600 handle 500 & 600 ft/lbs of torque, respectively.
The Tremec TKO's are completely different transmissions and larger than the
T-5 but not as large as a T56. The TKO is based upon the old top loader
design. Tremec purchased the T5 design from Borg Warner and so now makes
the T-5 and I believe the T-45 and T-56 as well.
As to what a T-5 can handle with the right aftermarket parts, a friend
runs a drag race Mustang that makes over 500 HP at the rear tires and
runs the 1/4 mile in the mid-9's. Up until this year he ran a T-5.
Granted it had an aftermarket case, input and output shafts, gear set
etc. but it withstood 7000 RPM dump-the-clutch launches on slicks in
much heavier car than an MGA. It's traction, weight, and torque that
kill transmissions and with a V8 MGA you'll only have 1 of 3.
There was an MGA V8 at the local (St. Louis, MO) Easter car show, built
by John Mangles:
> I was going to build a 300" Rover/Buick stroker motor for my (very slowly
> evolving) MGA V8 project. Then I realized that to support 300"I would either
> have to use either Wildcat heads (about $4000+ when all set up)or blow/turbo
> the engine.
Well ported Buick 300 aluminum heads will support 350 HP in a street engine
and 400 HP in a race engine (with more compression and cam). My Buick 300
heads flow over 200 CFM on the intake side with excellent intake to exhaust
flow ratio and low lift flow. The area under the curve for the max cam lift
I plan to run is as good as some of the entry level Ford 5.0L aftermarket
|"Mark Barnhart, an automotive aerodynamics consultant who has built a couple of MGA V8's and helped with an MGA which runs at Bonneville, figures an MGA need 400 hp to maintain 140 mph. (My daughter is grown and the will is filled out)"|
I think your friend is off base. My road racing Twincam handily does 130 MPH with less than half your projected 400 BHP. It has more to go, but is limited by the length of the straights at most tracks.
I expect that Kent Prather's car does likewise.
I would not anticipate you needing more than 250 BHP to maintain (not just attain, as you can do that with less than 200 BHP) 140 MPH over changing road conditions.
And I agree with Bill Guzman - high output MGA V8s tend to be show, not go cars and they make lots of noise and smoke - until something breaks. Same with MGBs.
You just don't need all that torque - go the horsepower route instead with a smaller engine, perhaps turboed, that doesn't have the massive torque low down, takes up less room, and gives you the power you want at top end.
|Dan's correct. I mistyped. The Tremec TKO is not a T-5. It is a beefed up Tremec 3550. Stronger than and mortal T-5. A bit larger, too. Can be had with GM Bolt pattern (same as Muncie & T-5), road race gear ratios, and in either 5 or 6 speed. I want one for my '68 Camaro!|
Bellhousing, still looking for good info. Standard GM bellhousing may work. Upper right bolt hole is deleted from LS1 block. Can't be drilled, so leave it out.
|Try Dellow Automotive (on the net) they make a variety of bell housings to suit various bolt patterns. They ship everywhere. The toyota supra box is smaller than the MGB box, light and supposed to be good for up to 500bhp.|
|Here's another clutch, complete with starter gear:|
|> I would like to do the Silver State Classic where they shut down 100 miles |
> of Nevada highway. You enter a class, for instance 140 mph, and drive the 100
> miles, targeting an average speed meeting but not exceeding the 140. Some
> sections are slower, some faster.
I'm an aero engineer and have consulted with one of the Pantera club guys
that runs the Silver State. As I understand it, the 140 MPH class has a
tech speed of 165 MPH. Since you will run less than 140 MPH in certain
sections of the course (Highway 318, a 2 lane road), you need to exceed
140 MPH in other areas to average 140 MPG for the entire course.
> Mark Barnhart, an automotive aerodynamics consultant who has built a couple
> of MGA V8's and helped with an MGA which runs at Bonneville, figures an MGA
> need 400 hp to maintain 140 mph.
Was that crank HP or rear wheel HP? That seems like a high estimate.
When stock, my daily driver 1987 Mustang GT could exceed 140 MPH on
225 HP (SAE net). Your MGA may have a higher drag coefficient but
the cross-sectional area is lower so I wouldn't expect the product of
the two to be higher.
> I would not anticipate you needing more than 250 BHP to maintain (not just
> attain, as you can do that with less than 200 BHP) 140 MPH over changing
> road conditions.
Assuming you use 200 rear wheel horsepower to reach 130 MPH and his
aerodynamics are the same as yours, Kurt would need around 250 rear
wheel horsepower to reach 140 MPH. The power required to overcome
aerodynamic drag is proportional to the velocity cubed (drag is proportional
to velocity cubed but power is a rate (the rate of doing work) and thus
carries with it another velocity term:
Preqd = 1/2 * Rho * V ** 3 * Cx * Area
Preqd = K * (V**3)
200 HP = K * (130**3)
K = 200/130**3
If I did the math correctly, approxiately 250 RWHP is required to pull 140
HP = (200 / (130**3)) * (140 ** 3)
HPreqd = 249.795 at 140 MPH
This assumes top speed is a function of aerodynamic drag only. Rolling
resistance is ignored but since rolling resistance varies to a power of
less than 3, the assumption is conservative. This also assumes optimal
gearing, ideal weather conditions, etc. and only predicts terminal velocity,
not the time to reach that velocity. The Silver State race is well above
sea level so the air density is lower (engine power will be less but so will
aerodynamic drag), the terrain is not level, and excess power will be needed
to accelerate at a reasonable rate. Also, power at the rear wheels is
considerably less than that at the crank as measured on an engine dyno.
Now assuming Kurt wants to reach the 165 MPH tech speed, he'd need
HP = (200/(130**3)) * (165 **3)
HPreqd = 408.9 HP at 165 HP
|Good information everyone..|
Jumping back to the T5, a T5 in a Camaro V8 with all the options can be upwards of 3,600 Lbs. The weight combined with a modified motor producing more then 300 BHP and torque to match can snap a standard T5. The happens generally on take off during hard launches or slamming it into second gear.
Removing the weight factor and going to a 1,900 to 2,400 MGA/MGB can add how much these things can take.
Another factor is rear axle ratio and how good/how much rubber is under the rear end of the car.
I bet there is either a factory bell housing that will fit an LS1 or an aftermarket unit already available with all the conversions on the market right now.
That said, even though 6 are not needed, I wouldn't mind a 10 speed split shift in my cars- I just like changing gears.
|BMC Brian McCullough|
|Dan, plus another 100+ hp for margin of error. Cross winds and rate of acceleration after slow downs. It would require addional hp to accelerate from 130 to 160 in a accepted good rate of time and then maintaining the speed would require 400+ hp|
Brian, it does not matter if the car is light, it's the torque transfering from the input shaft to the intermidiate shaft, that is where the weak link is in the T5.
There are special cut shafts for the T5 that takes up to 500 lb of torque, not cheap.
|Was just reading an article on the D type Jag.|
240 BHP = 170 MPH.
|Thanks for the info and comments guys. I have decided just to build a 300" Rover-based engine rather than use the LS1. Probably would be more interesting to build that anyway. Thanks again.|
This thread was discussed between 04/05/2006 and 19/05/2006
This thread is from the archives. Join the live MG MGB GT V8 Factory Originals Technical BBS now