5 ports, 8 ports and about 8000 rpm
Turbo Mini Forums

Now, this recent thread on the south african 70.2mm cranks has got me thinking, I would love to do a short stroke screamer, but it seems pretty well proven that a sorted 1275 engines can take 8000 rpm when built well, i.e jimsters and the don engines seems to hold together well despite mental power and revs, not that they cover all that many miles.

I would like to keep with the 5 port engine, but it seems that most engines on this site hit maximum power at about 6000 and drop off quite steeply after that. I would like an engine that pulls strong to 6-7 ish then carries on to 8 while retaining some sort of acceptable road and off boost characteristics.

The way round this appears to be moving to an 8 port head, with the obvious engineering challenges involved in fitting it and fabricating manifolds.

I was wondering whether using the shorter stroke crank, and the 5 port head could be used for a recipe to make a 5 port turbo engine rev to the numbers I would like. obviously there are issues such as preparing the block, and the push rod situation to overcome but this has been done in the past.

Turbo selection I appreciate will also have a significant bearing on allowing the engine to rev


Thoughts please.

funny that, i been thinking the same thing. the problem i came across is findly a suitable cam to do such task.

http://photobucket.com/quintonrose

Ok Lads a few reasons I am going for a short stroke crank,
the car I am putting this engine in is a 1963 Mk1 I want to turn it into a Cooper S Replica. The 1071 was introduced in 1963 so the obvious choice.

Second reason I have built 850's, 998's, 1098's, 1275's, 1380 and 1400+ but never built a over square engine only under square.

3 reason Its a little different.

no none of my reasons are max power or high hp.

Short stroke engines although rev very well don’t produce as much torque as long stroke motors, so really aren’t especially suited to the turbo application.

A short stroke will easily pull 8K rpm but most likely wont be very nice anything less them 3K due to the total lack of torque with out RPM.

minimole from your description I think a well sorted 1293 K16v would produce every thing you have said for a lot less effort that a 5 port short stroker.

I would say this this is down to cam and turbo choice. Most people make use of the turbo engine torque and forget about reving engines, after all this is what breaks them. If you want it to rev choose a cam that will allow it to rev.

Obviously trying to have a revy engine and a docile around town engine is more difficult.

http://www.twin-turbo.co.uk
http://www.hillclimbandsprint.co.uk/default.asp

A man without a project is like a like a woman without a shopping list.

pk power on mine is 6700 i think ,and was still climbing ,theres a print out on here somewhere .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

My rev limiter was 7k and it felt like it wanted to do more? obviously not sure if it would.

Got a 266 cam t3 turbo,

Rick

Robert - what turbo, cam, head combination do you have on that?

Whilst it was a long time ago....

My turbo engine last used the SW5, and had no problem whatsoever in making good use of 7500rpm, although I tended to shift around 7000rpm.
Even with the MG Metro cam, I had no problem making use of 7500rpm

For a very brief time I did use a Kent 286 n/a profile.

It lost all driveability and power below about 2500rpm, but it did rev no problem to 8000rpm, pulling strongly from about 5000-8000. It was horrible everywhere else though
The car was totally destroyed though. And despite the higher rpm ability, in no way was it faster.


With the SW5 or MG cam, I could still easily pull WOT in 4th from 1000rpm.

With the big cam...that was closer to 2500rpm.

9.85 @ 145mph
202mph standing mile
speed didn't kill me, but taxation probably will

if you search for "gt17..." info about it is there .

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

Hi,
Turbo motors are best as long stroke engines. Forget revs, torque is what you want! As low down in the rev range and as widest powerband you can get. When your torque drops off change gear!
A point in fact would be the difference between a 2.0 and a stroked 2.4 Cosworth engine. The amount of extra torque and better driveability is night and day in comparison.
Cheers,
Gavin :)

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My Mini build diary

saying when the torque drops off change gear, i have tried this in a desil not sure if it makes alot of differance, being a diffrent fuel, but going on after the torque curve droped off and power was still quicker than changing how you just said when the torque and power band drop off. did a little competition at my old work with 407 2.0l td's

Edited by Paul R on 27th Mar, 2009.

Drives
-Ford S-max Mk2 Ecoboost
-Rover 100 VVC #2 - track project

Searching is all you need on TurboMinis

I guess i cant comment changeing to a bp320 next season lol

if your going to rev it your going to have to size the turbo properly... ie bigger!! and in turn your going to suffer alot of low down loss and drivability!!

not with my gt25v turbo..... lol