I know its cheeky of me to ask... (Turbo vs NA)
Turbo Mini Forums

I have two engines here, a 1275 MG metty, and a 1275 Metty Turbo.

Thinking about doing one up, but not sure which I want to go for... the NA or the turbo.

The NA would be easier and cheaper, and that would be a high-ish bore, 1330.
Where as the turbo will just have a higher boost, and a stg2 head.

Expected power
- 1330 about 100
- Turbo about 110

I know I keep on and on, but does anyone happen to live close-ish to Hereford/Worcester, that has either of the above, that I could have a go in? Just to see what they both feel like??

I know its cheeky, but I am half and half and which to choose.

Thanks

Mod edit: moved to tech, and added a bit to the title for searches.

Edited by AlexB on 18th Jan, 2006.

The turbo will always feel faster, just because not only will it produce more power, but also produces a HELL of a lot more torque, lower down the rev range.

User "Nic" on here lives near Hereford. He also has one of the faster turbo minis in the country, I believe his was the 4th fastest car at the 2005 mini showdown. He may take you for a spin if you ask nicely. In addition if you have any single sisters who are not too picky this may help your chances considerably.

The thing thats putting me off, I think its from driving diesels too much. Is that the turbo won't kick in till 3200rpm, to me that sounds high. I have serched the forums now, and read most if not all turbo engine matters, but one thing I couldn't find out, is what rpm turbo engines will be safe at??
I know a NA would be good for 7k rpm...

Not only that, but the cost to build a turbo is silly! £500 for a stg2 head!!

I will contact Nic, and see if he's around. :)

A turbo engine will turn the same RPM as a NA engine with an equivalent bottom end.

However, you won't NEED to rev the turbo so hard. For e.g. a NA 1293 with a 286 cam producing maybe 100bhp, will require revving to at least 7500rpm to get the best from it. However, a 100bhp turbo engine will make that power quite happily without going much over 6000rpm, and unlike the NA engine, will idle and generally behave itself better in heavy traffic for example.

Good answer!
Also I have been clicking though the threads, and with a NA engine, a SW5 cam is good for bottom end grunt, what are they like on a turbo? or would a 286/SW10 be more suited for a turbo.

I pretty much sorted for the bottom end, and I am getting my std head, "worked" on, i.e to stg2. so its only the cam and boost, I need to fiddle with.

My ideal engine would be to have something that grunty low down, before the turbo kicks in, but once the blower does come in, I want it come alive. This is a weekend, odd trip into town type car, so want something fun, but still behave! :cool:

A turbo cam profile is rather different to the NA profiles, as they require extended exhaust timing to empty the cylinder more effectively and make the turbo spin up. The Avonbar turbo phase 2 cam is the popular choice on here at the moment. The phase 3 is a bit hairy for road use.

This thread rocks. Well done Tom!

I've had a tweaked 1275GT, with twin carbs etc, and now i have a fairly normal turbo motor.. the turbo is a million times more fun to drive, and it took me to work and back with no issues last week.

It is nice to offer some subjective advice to someone who has been and done their homework already, rather than the common novice questions we get!

Noticed this has moved, took me a while to find it!

I had a perfectly writen down list of parts for a stg3 1330, but then I was given this turbo motor, and well, I really couldn't make my mind up to which to have, as I have never driven a mega tweaked Mini, let alone a turbo Mini - or anything petrol driven turbo anyways.

Thanks very much for that spot of info, I think thanks to the caltaloge of info, I am 99% sure a turbo motor is for me.

Not much more to add really except to say turbo engines are under much less stress as well than a highly tuned NA motor. Much better street engines. I had a mental 998 NA and it was fun but a pain if you're not in the mood for it. Turbo power by next week for it :)

The turbo's don't kick in until 3200 rpm is a load of old cobblers, even Will and Ben's car, a low comp 998 race engine builds power from less than this. That's the sort of sillyness some people reproduce on some forums who have never driven a turbo mini. With a phase 2 cam, the turbo comes on lower than stock rpm.

If you go for a T2 conversion and a good build, MG metro NA cam, then you can expect 170+ ft lbs of torque from your 1293! That's TDi torque in a mini. As Tom said, it's torque that provides fun :)

Heads...hmm. Well most peeps here run near stock heads or home ported with the chambers opened up to reduce the CR. A top head will make little difference for a street driven engine. 10 to 15 hp? You can always save up and add a head later and get the basics sorted. The cam choice is far more critical. Forget SW10, 286's etc, more is NOT better for turbo cams.

Benross had great results from his phase 2 cam, I think over 140 bannana on 12 psi with his own ported head.

Go for torque and forget the big hp bragging rights and you will be a very happy person.

Good luck and keep us posted!

Peter

Editor

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Seven Magazine
The brand new quality Classic Mini Tech and Journal
Issue 1 out late 2027.

turbo spin up to boost all depends on the ar of the exhaust in let turbines.

my old t3 with a .26 ar spun up about 2500 rpm weres my new t3 with a .35 exh turbine spins up at about 3k

always looking for them bigger bunches of bannanas

Old T3 had .25, and new one .36 Hoggy :)

Might sound silly now, but what do you mean by .26 and .36? What does this signaify?

I have a good look at some builds that have been posted on here, could you tell me, is my build ok, and would it with stand anything...

1293
std stg2 head
8.3 C/R
Turbo dished pistons
Phase 2 cam
12 psi blower (was looking at 15) (T3 for ease of fitting, not got onto T2 as yet)
Recon'd GT box, with a trans X diff, and 3.2 final drive
S/C drops
Orange clutch kit
Dump valve

Would this be a nice torque/powerful motor?

0.25 and 0.36 are the A/R ratios. Do a search on here or on general turbocharging sites for a better explanation than I can type in here.

Spec sounds OK. However you need to be more definate on a few things; Pistons? Made by who? Cylinder head volume? Needs to be large to get your CR down. Gearbox? Standard helical gears won't live long with 12/15psi to be honest. Clutch I'd say that a grey is more realistic.

Just a few things to consider.

Wow that was quick.

Yes I was going to use a heli cut, so S/C would be wise to use then?
I was going to use the std, and get it worked on.
Pistons, would most prob be morspeed, might see if he'll so a short engine.

go turbo! my car should be back on the road ini a few weeks, ill take you out in it then and you will definately be going turbo!

Thanks Nic, looking forward to it already

Please let me know, I don't mind paying for some jungle juice if need be :)

If you go in Nik's you definately won't be bothering with nat-asp...

I can't wait, getting the Mini on the 27th, so be preped to see pics

and 'in car' video????

Edited by turbodave16v on 22nd Jan, 2006.

if its a choice between a Race N/A engine

and a turbo Race engine

i can assure you the turbo will win EVERTIME!

Edited by BENROSS on 2nd Feb, 2006.

dog ,my turbo starts boost at 1800, if yuo keep the cam timing down in duration then you ll get boost nice and low with a .26 a/r turbine housing . ,also mine puts out 114 rolling roaded bhp on 3.5 to 4 psi stock wastegate ,with no modulator .so you see you dont need al ot of boost to have fun with a good head cam combo.
regards robert.

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

whhoops .25!!

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

yes stock metro t3 .cam special one off, my own design .but prob similar to the phase 2 in most ways.that was with a 9.3 to 1 cr though ,which does tend to bring boost in a bit earlier.regards robert.

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