14 replies to this topic

[sam138]

Just wondering if someone could give me an idea of the potential power of the below spec on my engine that I’m building ? I’ve got a supercharger kit and really want to work out which way to go in terms of just a 1380 or supercharger it as well.


1380cc A plus with power max pistons ( P20659)
Minispares Evo 001 camshaft
1.5 forged rockers
Minispares MSE4 cylinder head
MED ultralight clutch kit
Rebuilt standard gearbox with 3.1 final drive and x pin diff

Edited by sam138, 05 February 2022 - 10:23 PM.

[nicklouse]

Don’t bother with the 1.5 rockers. 
 

enough to scare the crap out of you.

[GraemeC]

Should be capable of making somewhere north of 90 brake, but it will depend how well everything is optimised and how well built it is.

[nicklouse]

Very similar to the build here that I did a few years back.

https://www.theminif...das-gold-black/

[sam138]

Many thanks for the help

[Cooperman]

You bigest gain will be with mid-range torque rather than lots of top-end power. That will be a great engine, but make sure the compression ratio is correct for the boost you will be running and the distributor advance curve is optimised for the build specification.

With a forced induction engine you will need to match boost, comp ratio, piston quality and distributor curve. Get any of those wrong and it will be expensive when it blows up. I had to rebuild a turbo-charged engine where the boost was not matched to the rest of the engine, it had a standard distributor fitted and a static CR of 9.5:1. After about 10 miles a piston cracked and caused a lot of damage.

A supercharger is easier in terms of boost because it is a mechanical system rather than a turbine and thus boost pressure can be set by mechanical gearing without a 'waste gate' to be set/calibrated.

[sam138]

Is it possible to get to that magic 100bhp mark in NA form or will the car then not be suitable for road use in terms of power band being higher up the revs ? I’ve also had a look at a 7 port head option.

[nicklouse]

Is it possible to get to that magic 100bhp mark in NA form or will the car then not be suitable for road use in terms of power band being higher up the revs ? I’ve also had a look at a 7 port head option.

Why? Torque is what you want. And lower in the rev range the better.

[IronmanG]

Is it possible to get to that magic 100bhp mark in NA form or will the car then not be suitable for road use in terms of power band being higher up the revs ? I’ve also had a look at a 7 port head option.

My experience with the '7 port option' is dont bother

[Tones61]

In n/a form,
90-100 bananas

[sonikk4]

 

Is it possible to get to that magic 100bhp mark in NA form or will the car then not be suitable for road use in terms of power band being higher up the revs ? I’ve also had a look at a 7 port head option.

My experience with the '7 port option' is dont bother

 

 

Very very expensive. Ask me how myself and IronmanG know.

[sam138]

Is there any benefit of using a set of twin carbs rather than a Hif44 in terms of power/ torque ? I’m now looking to just keep the engine in NA form but want to maximise the power for a weekend car.

Reading this article they got mid 90’s from a 1330cc with similar spec to me with good torque.

https://www.calverst...er-test-result/

Edited by sam138, 20 February 2022 - 12:23 PM.

[whistler]

Should be capable of making somewhere north of 90 brake, but it will depend how well everything is optimised and how well built it is.

My wife's 1330 makes 90 bhp/89 lbft with evo 001 cam, matching distributor and MG Metro head so the OP's should make a lot more than 90.

[Cooperman]

For a road car, the torque is more important than bhp, especially with a very high FDR like 3.1:1.
With a high FDR, the gearing will be effectively wider, which emphasis on max bhp normally results in a narrower power band.
These factors are mutually incompatible for optimum performance.
Thus for the road with a 3.1:1 FDR, aim for really good torque from around 3200 rpm up to around 5500 rpm. To get 100 bhp will mean peak power at around 6000 rpm and a more peaky torque curve. Fine for some competition with a low FDR of, maybe 3.76:1, but far from ideal on the road.

[MiniCarJack]

Is there any benefit of using a set of twin carbs rather than a Hif44 in terms of power/ torque ? I’m now looking to just keep the engine in NA form but want to maximise the power for a weekend car.

Reading this article they got mid 90’s from a 1330cc with similar spec to me with good torque.

https://www.calverst...er-test-result/

 

On paper a HIF44 on a good manifold will give you all the performance you need for a road car, and will be easier and simpler to set up and maintain. That said I've now opted for twin HS4s on my own engine and the throttle response is fantastic (which is amplified by the lightened flywheel setup), and it feels like it "opens up" more above 3000-4000rpm, plus the twins just sound and look great - but I can't really say if they give any other practical benefit, my main motivation was that I've just always wanted twin carbs and they really suit a Mk1 engine bay.

 

For comparison with your engine spec I've got a 1330 with a JW Engines ported big valve head, Swiftune CSI distributor, Swiftune SW8 cam and 1.5 roller tip rockers - all going through a close ratio gearbox with 3.44 ratio x-pin diff and straight cut drop gears. I've not had it on a rolling road yet but it goes like stink and has a nice balance of top end power and a decent torque curve based on how it feels on the road. I'm expecting it'll probably make around 100hp(ish) and 90ft/lb of torque when it gets a power readout, but big numbers aren't necessarily the goal, it's more about the real-world drivability.

 

Not sure if that answers your question very well but just sharing my own experience 

Edited by MiniCarJack, 20 February 2022 - 09:43 PM.