Spitfire & GT6 Forum

Greetings All,

I wanted to share photo's and Dynamometer reports for my 1978 Spitfire. Last fall, the original cast iron exhaust manifold cracked in half so I was forced to make some changes. My car was all stock original with only 32500 miles on it when this happened. I decided to transform my engine to European stock under the hood. I purchased the 4-2-1 exhaust heade, and a used set of SU HS4 carbs with the linkage. Also upgraded the exhaust to the high flow Falcon SS exhaust and SS muffler. I removed the air pump, catalytic converter, EGR, valve and the rest of the pollution crap. I also had the engine head redone with all new stainless steel valves, new springs and upgraded valve guides. This really cleaned up the engine bay as you can tell from the photo's of before and after. The Dynamometer report shows the engine hp and torque at the rear wheels from the original motor and the RED lines are the results from the new motor. The result was an increase of about 12 HP and you can see from the graph it now has much more torque and HP over the usable RPM range. The Wide Band graph on the bottom is graphing Air/Fuel ration Vs RPM. All in all this has made the car a much better driver. I no longer have to race though the gears to keep up with traffic it has made a hell of a difference. Oh, the gas milage increased from 26 MPG to 32 on the why now with the dual carb setup. So, this is the reality of what you will get with stage one tuning on your Spitfire. This was the first time I ever removed the head from an engine and it really wasn't that hard of a job. Learning more about cars and working on them is why I got my Spitfire and I sure have learned a lot.

Chris Kalishek
Green Bay, Wisconsin

OUTSTANDING! I think I probably would have shaved the head, just enough to get to Euro compression too, but nice job! The difference at the top of the tach is staggering!

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Matthew
1960 Triumph TR3a
1970 Triumph Spitfire MK 3
2012 Mini Cooper SS Convertible
2018 Jaguar F-Pace
2018 jaguar XE

Did you shave the head or increase the CR?

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Dave
1970 Spitfire Mk3
FDU 78359L
34/11 (Jasmine yellow/Black interior)

1962 Triumph TR3B
TCF 575L
Signal Red/Red interior

If this is still running the stock cam I am amazed that the power keeps comming like that.

I assume you have the stock ABN needles in the carbs, the A/F looks very steady.

Well done! This looks like a win win win conversion.

Now, do you take it to the next level?

Thanks for sharing this! There's always lots of speculation around here about what these changes will gain, and you've given us some real before and after numbers. I see the prices of all those parts going up now tho'

If you didn't raise the CR or cam, these gains are even more impressive. Either way, it was worth the effort. Well done!

Surely must be an uprated cam?

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Andy&Sherry
1974 Spit 1500 Carmine Red
1977 Spit 1500 Pink Panther Pink

Always learning something

Now if you were to just bolt a DGV Weber on and go for another pull........that would be interesting

Incoming!

Hello, What I found out is that my 1978 Spitfire has the Dome top pistons, not the flat top piston so You would be unable to shave enough off the head to raise compression from 7.5:1 to what the cars in Europe have 9:1. I would have done t if it was doable, but it would be a lot more work and expense to change the pistons out. I just really like how much this has cleaned up the engine compartment. I have also noticed that my cooling is Better than with previous engine setup. On my temp gauge the needle is right in the middle of the range, exactly. Before I made the changes to the engine when I would turn off the car, then just turn key to on position the engine temp gauge would rapidly climb all the way to the top and stay pegged there. Now, with the new engine setup the temp only rises up one notch higher than when the car is running at temp. So, obviously the engine is managing the heat much better, this may be because I did the valve job on the head and maybe opened up the water ports? I was considering going to the EVANS waterless coolant but I don't see any need now that the car is cooling so well. This was not cheap, the parts I added to the engine ,exhaust, muffler, header, intake manifold, dual carbs, valve cover, hoses, misc. came to about $2000.00, so that means it cost about $200 per horsepower!

-Chris

Hello, Nope, no new cam or increased valve size. This is real world result of what you get by adding dual SU HS4's and the 4:2:1 exhaust header. I had a burnt exhaust valve in number two cylinder so the head was redone with uprated valve guides, stainless steel valves and all new springs. If you take the Dyno results I have provided and increase the numbers by 15% it equates to about 53 HP ate the engine for the original motor setup and about 67 HP at the engine after.
-Chris

Hello, My friend has a 77 Spitfire and he put on the Monza exhaust, Pace long tube headers, and a Weber side draft carb. I am trying to get him to put it on the Dyno so we can see the difference. The 4:2:1 header I added as you can see from the dyne graphs, really gives great torque through the whole RPM range. My understanding is that the long tube header should give better HP and torque but only at the high end of your RPM range.

-Chris

Hello, Stock cam, stock size valves, and the standard needles in the dual SU HS4 carbs. The header and carb setup would be the same as European cars.

-Chris

Hello, This is the reason I went to the trouble of uploading this information, so all Spitfire owners know what to expect when you buy the performance goodies for your car. It's a little scary bringing your car to the Dyno since they make you sign the papers saying there not responsible if your car Explodes on the Dyno. Then you watch them run your engine all the way to redline, its a little unnerving! Even with the small HP numbers, the guys at performance shop were impressed with the Spitfire.
-Chris

Is the 4-2-1 manifold the cast (Euro) factory version of the tubular 3Y?

I made the change from a Monza 4 into 1 to a modified factory 1147cc tubular 4-2-1, and I honestly felt it made an improvement in torque below 3k rpm (which I feel is more useful than an improvment after 4500 rpm)

I was also surprised at the cost! I guess things have changed in the last 25 years.
My HS4's came from the Spitfire Graveyard all-in for about $100 Can. But I did later put in a full Burlen kit with shaft bushings and plain butterfly's.

Hello, I got the 4-2-1 Header from Spit Bits in California, it is SS and comes in two pieces so it was relatively easy to install. Just had to do a little grinding on the flanges to remove some high spots that weren't allowing the header to seat against the manifold, so I had a small leak the first time I installed it. The cost was for all the exhaust system in stainless steel, the header, the dual carbs, linkage, two carb repair kits, new valve cover, air box, heater/radiator hoses, new vales (stainless steel), springs, valve guides, head reconditioned and all bushings, shocks ball joints, grunions, and springs in front end. I got all the parts for around $2000 USD. I really want to find a good used Overdrive to add to my car. I don't care for cruising at 4300 RPM to keep up with traffic at 70 mph. Does anyone out there not think the Triumph Spitfire needs the optional overdrive? Have you ever heard of anyone ever removing an overdrive because they were not happy with it?

-Chris