486 replies to this topic

[PhilipGCaldwell]

Why fit a different camshaft to it if you're scared to utilize it?

Let it rev!

I agree to some extent, it would be nice though to have something where the power is a little lower down the rev range so I dont have to make it scream everywhere!

If the engine has to come out for any reason I will change to a 266 or something similar

also future modifications will be to change exhaust as the one fitted isnt suited to a 998, its a 3 inch fletcher, when I bought it at the time I had no idea on engines or whatnot so just thought bigger was better, need a smaller unit

[brum,brum,mike]

have you got any onboard footage?

thinking of building a similar spec engine, would be great to see what it goes like

[jaydee]

The beauty of the 998 is that at 4.5k rpm goes bang to 7k rpm..one of the reason why i ditched the 276 because i was revving it all the time up to 7000/7200, engine wont have lasted long.

[PhilipGCaldwell]

This is my printout, as you can see the torque has pretty much peaked, at around 190lb/ft, the hp figure is nearly a perfect straight line that shows no indication of slowing down, so looks like it will peak somewhere in the 50's



This is Paul's printout, the torque peaking at 239 lb/ft, but notice that the hp figure has pretty much peaked by 5000rpm

[Tommyboy12]

190lb/ft!?? That cant be right! Thats diesel/turbo territory!

Even the A-series turbo only managed (albeit limited) 85lb/ft!

[PhilipGCaldwell]

god knows, thats just what the graph says, does sound wrong

[PhilipGCaldwell]

maybe it reads 18.7 and 23.9 lb/ft, I think the decimal point might be obscured by the line on the graph? My old 998 only only managed 38lb/ft toque so 187 rather too much of an increase!!! Maybe its how Im looking at the graph,hmmm, anyone?

Edited by PhilipGCaldwell, 20 November 2012 - 03:02 PM.

[Tommyboy12]

I would have said it was in Nm but that still puts it around 135 lb/ft. I think the RR needs re-calibrating!

[Tommyboy12]

Reversal of the HP equation shows it to be about 60lb/ft @ 4000rpm. Which sounds about right!

Equation is:

HP = (Torque x RPM)/5252

Edited by Tommyboy12, 20 November 2012 - 08:16 PM.

[tb205gti]

That printout is not right. :/ Only 5 points measured and torque that is WAY off..

[OfMini&Men]

Good little engine you've built, good to see small bore's being used instead of rusting away.

I'm currently finishing off my mini sticking a stage 1 998 in then finish building a 1060 off set twin cam super charged engine once I've picked the head and charger up should be a mean little bit of kit.

[Sam Walters]

5000rpm = 45hp
4000rpm = 32hp
3000rpm = 20hp


HP = (Torque x RPM)/5252


hp*5253/rpm=torque



20*5253/3000= 35
32*5253/4000= 45
45*5253/5000= 47

[steven]

just read the whole thing lovely engine !

[Cooperman]

For a 998 with a 276 to work you simply have to rev it to around 6400 rpm. Peak power will be at about 6200 rpm.

It does sound as though you have 'over-cammed' it with the 276, but you clearly realise this.

A 266 will peak at about 5800 rpm in a 998 which is fine so long as you do the RR run to 6000 rpm.

Maybe you could consider the old BMC AEG510 Cooper 'S' cam which is very nice in a 998 and the one I built with a 510, plus a lot of other work gave 66 bhp at 6000 rpm.

The 998 does like to be revved, so don't be afraid to do so.

[Steve220]

Holy thread revival batman!