Best way to add 20-30 bhp to TC?

[dunclentdr]

My Plus 2 is running the original TC engine on Webers. The car seems much less sporty to drive compared with my DHC which has Strombergs and I think is slightly more powerful than standard.

I have had the Plus 2 on a rolling road and it puts out 100bhp.

The Plus 2 is a nice early original looking car and I would like a discrete way of adding 20-25% more power. Is the best route some work on the head, maybe uprated cams and exhaust improvements?

Advice (and costs/UK suppliers) welcomed.

Thanks

David

[gjz30075]

Keep in mind the +2 is about 500 pounds heavier than the Elan. Do both cars have the same diff ratio? A lower (numerically higher) ratio will help with performance. If not already, going to a 3.9 or 4.11 will help, for not a lot of cost.

Greg Z

[elan66]

Hi David,
rolling roads can vary a bit,but is that 100bhp at the wheels and what spec is your plus2 engine,ie. is it a big valve.If it is not i would guess that an earlier engine would put that sort of power out at the wheels.Did they do any tuning or advise any tweaks while you were there.If it is a big valve it may need a good tune up,is engine healthy etc.You could fit something like QED 360 spec cams (re grind)but you will also need to re-spec the carbs etc but should give you 135 -140 but the rest of the engine needs to be in good nick,someone far more knowledgeable than me will be along in a minute with much better info
regards
paul

[dunclentdr]

Thanks - it is an early engine so is a few hp down on factory spec but not bad 45 years on. It isn't a big valve and I guess one option is to have the head re-done to big valve spec.

David

[rgh0]

100 hp at the back wheels is pretty healthy for a SE twin cam which the early Plus2 had.

A high lift cam such as the QED 420 is the best way to get another 20 to 30 Hp. Porting and bigger valves will also help combined with a larger bore exhaust manifold and tail pipe such as the TTR road system. 34mm chokes in the carbs and a rolling road season to get it all tuned

cheers
Rohan

[elan66]

Rohun is right(one of the much wiser i spoke of ) the QED 420 spec is better but more work i think as you have to uprate valve springs etc,the 360 spec being more of a modern sprint spec.,and easier to upgrade,but slightly less power.If you are going to do all that though you are into the dreaded while its all apart i may as well refresh the rest of the engine,its no point adding 40-50% power to a tired 45 year old engine.The exhaust will set you back about ?800+vat from TTR,and the head will probably cost ?1000 upwards depending on condition,a lot more with porting etc ,the webers will need rejetting etc so allow another ?100+,personally if the engine hasnt been touched before i would seriously think of renewing rings/bearings etc and refreshing the bottom end,should be good for another 45yrs only faster
Rohun can tell you better(take his advice)
regards
Paul

[rgh0]

Yes the high lift cams such as the QED 420 will require new spring packs and benefit from the bigger valves and porting. Proper porting on a twin cam is expensive due to the long inlet tracts but it will take you to the +30 hp end of your range. Without porting and if you just fit Big Valve Sprint specification inlet valves and the QED 420 cam you will be more towards the +20 hp end of the range.

The QED 360 cam is really just their Sprint cam equivalent and will only give you in the +10 hp range compared to the current SE cam you should have if your engine is standard.

Mission creep is always a challenge to avoid when you get into an engine so you needed to decide if possible on the state of the bottom end and whether you want to do work on that as well. If compressions are good and oil pressure is good and its not using oil then no real reason why it will not take the extra hp. But if it has had a long life and will need a rebuild soon then now is perhaps the time to do it

cheers
Rohan

[elan66]

Hi Rohan
(sorry to mis-spell your name )i am in process of rebuiding a plus2 which the PPO had kept the cylinder head and i have managed to aquire another head that is built to 360 spec.Would you consider the 420 spec. a worthwhile/noticeable step up
many thanks
Paul

[promotor]

Keep in mind (in addition to the weight difference already mentoned) that the Strombergs make the throttle feel much more responsive and help with low down torque due to their design. The difference felt between the Weber engine and the Stromberg engine may well be down to that initial "phase" the Strombergs provide.
Stromberg = good for street driving, Weber = good for looks and race track.

For my road car I am considering fitting Strombergs over Webers due to the above.

[rgh0]

In a 1558 to 1600 cc twin cam a Q360 will give around 125 to 130 hp. A Q420 cam will give around 140 to 150 hp depending on valve size and porting and other details. The difference is noticeable in an Elan

cheers
Rohan

[elancoupe]

..or, 360 cams in a 1700cc will give about 140hp, and over 130ft/lbs torque.

[rgh0]

and 1700cc with a QED 420 and the right porting will give over 150 hp

you cant beat cubic inches as they say in the US

cheers
Rohan

[elan66]

Thanks guys i guess i will have to give the 420 spec some serious thought,easier now than wishing later
regards
Paul