29 replies to this topic

[blake12345]

Hey,

Im wanting abit of a challenge so i was wondering if it is possible to get a 1098cc (1172cc at the moment) up to 100hp @ the crank? My engine is currently producing 70 with a very mild head and very bad exhaust leak. Im awaiting a delivery of an exhaust and new set of extractors and am planing on taking it back to the dyno to play around with some different Dellorto jet and choke combination. So yeh just wondering if people reckon its possible to get 100hp @ the crank?

Also how do you go about changing a cam on a 1098cc? Do you need to remove the gearbox of anything to get at the cam followers or anything like that? And is it hard to use a cam dial in gauge and get it all set and sorted?


Thanks Blake

[liirge]

Oooohhh there is don't you worry about that!!
the question is how much money do you have, and do want to do it the easy way (Forced induction) or the hard way (Normally Aspirated)?
And the cam can be changed without taking the gearbox off from the engine, as you have a small bore engine and therefore tappet chest covers allowing the removal of the followers, its just the big bore blocks that you have more fun with. in fact if you really wanted to, and have the acrobatic skills of the Moscow circus (slight over exaggeration) you can change the cam with the engine and gearbox in the car, but i believe you have to cut a hole in the inner wing, where the grill is for the radiator, to allow the cam to go in straight.

[Wil_h]

I think in NA form it is possibe, but unless you are building it for a reason (such as within the regulations of a race series) then it's going to be a very highly strung motor, with massively compromised drivability. And the RPM you'll need to run will reduce the lifetime of your engine quite alot.

As suggested above, if you turbo it it's an easy target with the result of a fuel efficient, driveable, reliable engine.

[Cooper-202S]

If your going to push the crank to that level of power your going to need to consider some work on the bottom end first. The 1098 crank is the most prone to flexing due to the minimal overlap between the main and the big ends.

IMO a centre strap is going to be a must as well as wholesale balancing of the crank and the rods to reduce the stresses to a minimum, note I'm not talking about deliberatly lightening just getting everthing properly dynamicaly ballanced to reduce the crank flex to a minimum. A high spec crank damper would also be a good investment.

As others have stated with a turbo you will get a nice reliable engine however if you have fitted flat top pistons you may run into compression ratio issues.

If you do take on the challenge can you please start a project thread as a F/A 1100 is a future (i.e. stalled by lack of funds) project of mine.

[mk1leg]

you will need an EN40B crank £1000...for a good 2nd hand wich needs resurfacing and polishing.........or you can purchase a new crank from...............(see minimagazine June 2010 page 84) £700-1350.........

[miniobsessed]

Plain and simple...

Forced induction will be your best option to get 100+bhp from your 1100... But you'll find you'll have to completely strip and modify your engine to suit the pressure and power.

If you're going N/A it's really only going to be possible by fitting a 'full race' camshaft and cylinder head and get everything else spot-on (timing, fuelling, etc...). This will make for a bit of a pig to drive.

All this said... Your engine will probably have a much longer and happier existence in it's current form so I'd either enjoy it (a mini kicking around with 70 odd bhp is nice and fun to drive while maintaining some level of reliability) or go for a modified 1275 or engine conversion...

[Fluffy]

I would like to know how you got the 70 bhp you have now.
I'm running a 'virgin' ( unmodified ) 1098, and would like to get started with it after I have the brakes sorted out.

[blake12345]

Thanks for the reply's.

Id like to do it in N/A form. as much as i like turbo theres just something about driving an N/A car that i like.

I only drive my car on weekends and its usually sitting at about 80kph (not sure what that is in mph) as alot of the roads around here are 80 - 90kph and then i do alot of mountain driving so it being abit of a pig to drive doesnt worry me very much.

Im thinking of getting a fair bit of head work done to make it breath alot better., then start to consider a 'bigger' cam. As for the crank i would like to get a really really good crank so i dont go breaking it. Is a billet crank stronger than a standard crank?

Um to get to where i am now with the engine i have spent about $5000aus on it. This has seen it have a 80thou bore, flat top pistons, 202 modified head, a cam but not sure which one, gearbox rebuild, 40DHLA on a redline manifold, an extremely leaky manifold and exhuast (which im waiting on a replacement to arrive) um and not sure if anything has really been done but yeh its pretty good to drive sounds awesome.

But yeh im planning on doing a D-Series honda engine or a 4EFTE Conversion (depending on which engine i can get my hands on easy) in a few years but until then i want to see what the 1098cc is capable off because i dont hear to much about people modifying them.

Edited by blake12345, 09 May 2010 - 01:54 PM.

[bmcecosse]

I'm VERY dubious about your claim to have 70 bhp at the moment - this is highly unlikely unless you have already changed the cam and fitted a large valve head. To get GENUINE 100 bhp from 1098 you will need a 1071 S block and crank - which at +10 thou will be very close to 1098cc. Strengthen it up with a centre main support and full balance - 649 cam and large valve S head (fully flowed) and a 45 Weber with good exhaust you should be close to GENUINE 100 bhp.
Frankly - from an original A series 1098 it's not going to happen unless you supercharge it. You just can't rev the 1098 crank hard enough to get the power - it snaps too easily. Could use a 998 engine as the basis - and overbore it till ~ 1098 - you could have more chance with that, but will still be v fragile compared to the 1071 S version.

[liirge]

Yeah a 998 +120 thou overbore is 1096.
However i would probably recommend just going the forced induction route, especially if you want the engine to last a bit longer than running in miles!!

[Wil_h]

Plain and simple...

Forced induction will be your best option to get 100+bhp from your 1100... But you'll find you'll have to completely strip and modify your engine to suit the pressure and power.

Actually, a 100bhp turbo 1100 will have a LOT less stress on it than an NA 100bhp 1100. A standard bottom end will easily be up to 100bhp on a turbo motor, no bother.

[liirge]

Plain and simple...

Forced induction will be your best option to get 100+bhp from your 1100... But you'll find you'll have to completely strip and modify your engine to suit the pressure and power.

Actually, a 100bhp turbo 1100 will have a LOT less stress on it than an NA 100bhp 1100. A standard bottom end will easily be up to 100bhp on a turbo motor, no bother.

you dont have to rev a forced induction motor to get all the power out of it!! unlike a NA race cam'd engine, that will put serious inertial strain on the bottom end.

[blake12345]

bmcecosse - I have 47hp @ the wheels which is about 70hp @ the crank. I have dyno sheet around here somewhere.

mmm right what kind of compression ratio would i need to run? and what kinda psi would i need to run to reach my 100hp mark? and would 100hp @ the wheels be unrealistic for a turbo 1100?


Thanks Blake

[samsfern]

naturally aspirate it with a BMW k bike head!

[blake12345]

that is another option. Does a BMW head conversion make that much of a difference?