11 replies to this topic

[cooperracer]

Hi

 

Soo....am in the throws of working out which head to get for my SPi, and have been researching heads available. I am a bit lost, so wanted to create a thread with a list of different heads, and also invite some help on comparisons, experiences, outputs and performance etc of the different products available.

 

I have a 1995 SPi Cooper, 70K. Plan on retaining the Rover ECU and also the standard Cam, so want to get up to around 80 bhp

 

Parts I am considering:

 

Cylinder head - ??

1.5 Roller rockers - ??

LCB - Probably a Maniflow LCB (maybe large bore, but not sure, any feedback?)

Exhaust - I have Fletcher 3" single side exit

Air intake - Either a cone or panel K&N

 

Cylinder heads for SPi:

Med 5 port Competition: http://www.med-engin...oad-competition

 

Avonbar: http://www.avonbar-r...75-Stage-4-Head

 

Keith Calver: http://www.calverst....ead-large-bore/

 

VMaxscart: http://www.vmaxscart...nder-head-work/

 

Slark racing: http://www.slarkrace...ngine-products/

 

Jonspeed: http://www.jonspeedr...=14475&cID=2089

 

Minisport: https://www.minispor...abs_description

 

Minispares: http://www.minispare...|Back to search

 

I dont have enough technical knowledge of the key differences between the heads, aside from potential build and workmanship quality.

 

Can anyone help me with recommendations etc?

 

thanks

 

 

 

 

[racingbob]

you may want to consider AC Dodd for a head as well and hes on the forum

 

and I personally wouldnt fit the fletcher 3" exhaust get a maniflow or RC40 for best performance

 

i would imagine you would need a superb head to get 80hp without changing the cam

[AgentHubcap]

I've been looking at the Keith Calver head and was told that a different cam (255 or 274) is a far better choice over rockers.

 

The minispares head is out of stock, so you may have to wait a while for that one.  

The Jonspeed head doesn't look like an uprated stage head (no porting).

 

I can't really comment on the others.  

[cooperracer]

Thanks Bob, yes, I'm probably being a bit unrealistic with aim of 80bhp. Is cam change engine out? I'll check out AC Dodd for sure, thanks for the tip. Yes I've read a far bit about RC40 as the only option for performance....will probably see that if the fletcher doesn't aid gains. I presumed (I'm a bit of a ludite when it comes to mechanics, but learning!) that the fletcher would be really similar to an RC40.

[racingbob]

Thanks Bob, yes, I'm probably being a bit unrealistic with aim of 80bhp. Is cam change engine out? I'll check out AC Dodd for sure, thanks for the tip. Yes I've read a far bit about RC40 as the only option for performance....will probably see that if the fletcher doesn't aid gains. I presumed (I'm a bit of a ludite when it comes to mechanics, but learning!) that the fletcher would be really similar to an RC40.

the 3" fletcher apparanty will lose power by being to big diameter, i have the maniflow probably the best.

my race mini only had 2" diameter and maniflow fast road is 1.75" as i have

 

check that the 1.5 rockers will work well with the spi cam you dont want to lose

low down torque, yes engine out for cam change and full strip down

i have the mg metro cam in mine which is a good cam been in there for 5 years now

[cooperracer]

Is that with the SPI system and standard ECU? I'm hoping to.keep a car that can be used in traffic etc but is a bit more excitig to drive.

[FlyingScot]

Talk to Keith Calver and AC Dodd about what you are looking for, they will give you the info you need. It's important to combine the elements properly.
As far as I was aware Racingbob the mg metro cam leads to emissions problem when run in a fairly standard Spi due to the overlap

FS

[cooperracer]

Thanks FS. Im going to give them both a call. I have ha a couple of emails from Keith and he has been really helpful. I've sent AC a note on FB too. What I'm finding confusing is quite a lot of contradicting info, which makes me think it must be small differences and like you say, it's all the ingredients mixed together...lots to learn but really interesting.

[ryomini]

Adding a good head should improve performance

1.5 rockers will probably just stress out the valve springs and make performance worse

I have found AC Dodd to be very helpful

I would be interested in your results

(1.3 full roller rockers may be a better bet)

[cooperracer]

Sure. I'll keep you updated. I've pretty much had responses from most of the suppliers by email, I'm going to call a couple when I have some free time and have a chat. Will keep this thread updated. Would appreciate anyone that has gone down a similar route sharing any experiences too.

[brivinci]

Calver all the way. He does a brilliant bit of work, is super knowledgeable and not only is a builder, but also a racer so he understands everything from one to another and in between. One of the best things is he is extremely honest and will actually undersell things if he thinks it would not be a benefit for the application.

 

Before you tear into the motor, best to do a full health checkup on it. Oil pressure, compression test, leak down test, and hook up to a ACR to make sure everything is in perfect shape and ready for the added HP's

[ryomini]

I thoroughly agree with brvinci on doing a full test of the engine as it stands especially a good compression test

 

no point putting a good head on a set of worn pistons (cough cough, I should listen to myself....)

 

take lots of pictures and detailed notes about everything you modify so you can step back if you need to

 

I ported the head added a SW5 and a light steel flywheel, throttle is light, response is nice and it's been sweet to drive (but is now in need of a new fuel pump so I haven't finished road testing)

for that price you have a pretty decent 80bhp ish useable engine - that's my experience so far

 

whatch this video it could help you too