57 replies to this topic

[neal]

See Racingbob's spec, low cost with bags of useable/sensible power.

Bob's mini goes incredibly well and is not far from the ideal fast road spec in my view. It's set up for the bends/ lanes and has power / torque where needed, not at the top end. Even before he fitted the new head, and when I was running a 1293 with a 286, he would leave me for dead driving the country lanes. Sure I had more horses, but torque is where the real power is in the real world and his little lump was by far the better on the road.

The only issue for someone replicating bobs spec is that he has an mg metro cam which is no longer available in its original format, but that cam could be improved on anyway with a more modern grind. My next build will be similar to bobs but I'll be running the minispares evo1 cam (also marketed as the 264) which is very similar to the mg metro but is a little bit more cam and with more lift. Essentially it's a more modern version If I didn't have the evo1 in the garage I'd consider one of AC's cams, probably his RS or RT.

Some very good points and some really good cams out there but lets not forget bob is running on a std. bore that has covered many miles but really well maintained. I think that a modest set up fully balanced, built correctly with a good choice of diff is the way to go. I think my next build will be along these lines in a stripped out street racer......Come to think of it Bob, can I have first dibs on your car when you get bored of it? mine is too pretty to drag the strip.

Edited by neal, 23 August 2017 - 08:16 AM.

[Mrpeanut]

See Racingbob's spec, low cost with bags of useable/sensible power.

Bob's mini goes incredibly well and is not far from the ideal fast road spec in my view. It's set up for the bends/ lanes and has power / torque where needed, not at the top end. Even before he fitted the new head, and when I was running a 1293 with a 286, he would leave me for dead driving the country lanes. Sure I had more horses, but torque is where the real power is in the real world and his little lump was by far the better on the road.

The only issue for someone replicating bobs spec is that he has an mg metro cam which is no longer available in its original format, but that cam could be improved on anyway with a more modern grind. My next build will be similar to bobs but I'll be running the minispares evo1 cam (also marketed as the 264) which is very similar to the mg metro but is a little bit more cam and with more lift. Essentially it's a more modern version If I didn't have the evo1 in the garage I'd consider one of AC's cams, probably his RS or RT.

Some very good points and some really good cams out there but lets not forget bob is running on a std. bore that has covered many miles but really well maintained. I think that a modest set up fully balanced, built correctly with a good choice of diff is the way to go. I think my next build will be along these lines in a stripped out street racer......Come to think of it Bob, can I have first dibs on your car when you get bored of it? mine is too pretty to drag the strip.

Neal, you're missing the point. With Bob's new head he's pushing out one more horse than my last build did. I'm convinced he got lucky on a dodgy roller or something but either way I'm not having that!!

[ACDodd]

Ok just to add, Bobs engine would be considerably better, ie 8 to 10bhp if it were based on a new bottom end. Worn engines are one of the ways power is lost from a given specification. Whilst the mg cam is good, it has simply been left behind in terms of torque production, idle quality and length of power band, by much more capable modern cams. If its torque under 4krpm you favour from your engine then 1.5:1 rockers would not feature on your spec sheet. I have found that best average torque between 2k & 5krpm is delivered when using a modern profile together with a rocker ratio of between 1.3 and 1.35:1 is employed.
Conversly if its a big torque number above 4krpm you are looking for then yes 1.4 or 1.5rockers will be your aim. Using 1.5 rockers on a mild modern cam can be benificial in extending the power band of a mild cam. There is a penalty though, and that is of increased wear. For typical road mileages, 1.3 nominal ratio works well for me, and gives a good compromise between life, and torque.

Ac

Edited by ACDodd, 23 August 2017 - 10:05 AM.

[neal]

 

 

 

See Racingbob's spec, low cost with bags of useable/sensible power.

Bob's mini goes incredibly well and is not far from the ideal fast road spec in my view. It's set up for the bends/ lanes and has power / torque where needed, not at the top end. Even before he fitted the new head, and when I was running a 1293 with a 286, he would leave me for dead driving the country lanes. Sure I had more horses, but torque is where the real power is in the real world and his little lump was by far the better on the road.

The only issue for someone replicating bobs spec is that he has an mg metro cam which is no longer available in its original format, but that cam could be improved on anyway with a more modern grind. My next build will be similar to bobs but I'll be running the minispares evo1 cam (also marketed as the 264) which is very similar to the mg metro but is a little bit more cam and with more lift. Essentially it's a more modern version If I didn't have the evo1 in the garage I'd consider one of AC's cams, probably his RS or RT.

Some very good points and some really good cams out there but lets not forget bob is running on a std. bore that has covered many miles but really well maintained. I think that a modest set up fully balanced, built correctly with a good choice of diff is the way to go. I think my next build will be along these lines in a stripped out street racer......Come to think of it Bob, can I have first dibs on your car when you get bored of it? mine is too pretty to drag the strip.

Neal, you're missing the point. With Bob's new head he's pushing out one more horse than my last build did. I'm convinced he got lucky on a dodgy roller or something but either way I'm not having that!!

 

LOL, Bob took his car to Janspeed along with a mate of his who both went to Slarkes previously, bob's mates car (untouched) produced the same power on both rollers, Bob arranged this on purpose to compare any differences between the two rollers, check with bob!

[Rusty1182]

ok so i have a good idea of what cam and rocker choice i could use.

what about the head

ported and polished and bigger valves

is there such thing as too big

do i need the larger exhaust valves?

[neal]

Ok just to add, Bobs engine would be considerably better, ie 8 to 10bhp if it were based on a new bottom end. Worn engines are one of the ways power is lost from a given specification. Whilst the mg cam is good, it has simply been left behind in terms of torque production, idle quality and length of power band, by much more capable modern cams.

Ac

Flippin heck Ac, if your saying that bobs engine would have made quote ie 8 to 10bhp more on a new bottom end, then this is crazy power for a simple build.

 

I might have to have a re-think about doing the odd cylinder head for a mate, I was only doing this as a bit of fun.

Edited by neal, 23 August 2017 - 10:27 AM.

[ACDodd]

Yes, I can get more power and torque with less cam and rocker ratio by using a new bottom end and a modern cam. Super mighty minis get 92 to 93bhp with a stock 1275 cam and 1.5 rockers for comparison. You don't get these figures without using the best components, so no 21253 pistons here, its calverst or omegas.

My own road engines using my ACD - RS cam get 87bhp and 92lbft of torque with 1.3 rockers and a factory smooth idle. Add 1.5 rockers and these go up to 97 to 99bhp and 97lbft of torque still with a smooth idle.
Department 75 dynoed an engine last week, machined by myself using a stock Head, no porting just opened out chambers to get the Cr correct and a 3 angle valve job, with mg metro valve sizes and scored 83.5bhp and 86lbft of torque with the RS cam and 1.3 selected pressed steel rockers on a single HIF44 Su. Power is there for the taking, you just need to eliminate wear and maximise airflow.

Ac

Edited by ACDodd, 23 August 2017 - 10:47 AM.

[neal]

I'm going back into my garage for a bit, finish off a cylinder head and have a think about all this........

[ACDodd]

I am porting right now too!

You don't need a bigger exhaust valve, I have passed the 130hp mark using a 29.4mm exhaust valve size. You need 35.6 x 29.4mm valves to get the most torque versus reliability.

Ac

[Rusty1182]

I am porting right now too!

You don't need a bigger exhaust valve, I have passed the 130hp mark using a 29.4mm exhaust valve size. You need 35.6 x 29.4mm valves to get the most torque versus reliability.

Ac

perfect thanks :) just what i wanted to hear :)

[nicklouse]

and you don't want 1:1.5 rockers. a matched set of standards or some 1:1.3 rollers if you really want the bling.

[Turbo Phil]

Should you wish to use it the MG Metro cam is still available from Kent cams part number KC500.

Phil.

Edited by Turbo Phil, 23 August 2017 - 12:54 PM.

[Rusty1182]

Thank you all for the help.

I will take your comments into consideration during my buying and building.

i just need to decide do i do the modifications over a period of time or collect all the parts and just do a rebuild / refurbish.

im tempted to have the engine removed and have a garage fit all the parts to my engine and do the cam and diff at the same time.

i would remove the engine my self but dont have the space or skills to do the cam