4 replies to this topic

[Minicfc]

Hey all, looking for bit of help. Finally decided to rebuild my engine, currently a 1275gt, and looking for a bit of advice with spec.

I am looking for something about 80-90 bhp same for torque, so I am thinking about a 1330, not sure whether I'm better rebuilding my gt engine or pick up an old 1275 and rebuild that. I know the gt engines are getting rarer so don't really want to bore this out to 1330

Need help with the cam, head spec, Gear ratio, ect

Spec so far:

1330 block
Crank reground, toughened and balanced, new bearings
Omega pistons, size?
Stage 3 head, spec?
Kent cams, 266?
Duplex timing
Gear box ratio 3.4:1

Looking for low end speed and torque, not really going for high top end. Want it to have good acceleration and pull around town, don't do a lot of motorway driving.

All help and advice is appreciated

[ACDodd]

Here is a couple of real world examples;


The engine is an MLMotorsport customer unit carefully screwed together by Andy Davies.
This one is a Fresh (500ish miles) 1330cc built to MLM road spec. It features a ACDodd rebuilt Morspeed stage 3 head (35.7 x 29.4mm valves mega +0.060" pistons, this combination giving 9.75:1 CR. ACDodd - RS cam installed at 106 degrees. It uses Minisport 1.3 roller tip rockers, Single HIF44 SU carb, cone filter, Custom ACDodd needle, Ignition utilized an ACDodd Custom curved Lucas 65DM4 electronic dizzy, the usual freeflow intake and exhaust system. Fuel 95 Ron Unleaded.

Produced figures of 85.9hp@ 5500rpm (flywheel), and 91.6lbft @ 4000rpm which is impressive given the spec.

Here are the exact figures if anybody want to plot them, runs taken in 3rth gear, power at wheels was 76.5bhp peak.
Correction factor 0.98672 today, DIN 70020

Rpm Bhp Torque(Lbft)

1000
1500
2000 29.53 77.56
2500 40.95 86.02
3000 51.35 89.90
3500 60.41 90.65
4000 69.81 91.66
4500 77.53 90.48
5000 83.23 87.43
5500 85.92 82.04

The result is I am very happy with the new ACD - RS cam more torque for the road base engine than anything else I have tested to date,


The next engine is a customer built/part ACDodd unit.
This one is a Fresh (500ish miles) 1330cc Cooper 'S' built to ACDodd spec. It features a rebuilt ported head (origin unknown) re chambered by ACDodd for 9.75:1 CR (33.2 x 29.4mm valves mega +0.060" pistons, Omega ring set. ACDodd - RS cam installed at 106 degrees. It uses Minisport 1.3 roller tip shimmed rockers, Twin HS4 SU carbs, cone filters, Custom ACDodd needles, Ignition utilized an aldon 45D4 electronic dizzy, the usual freeflow intake and exhaust system. Fuel 95 Ron Unleaded.

Produced figures of 86.84hp@ 5500rpm (flywheel), and 90.73lbft @ 3000rpm which is impressive given the spec.

Here are the exact figures if anybody want to plot them, runs taken in 4rth gear, power at wheels was 72.1bhp peak.
Correction factor 1.009102179 today, DIN 70020

Rpm Bhp Torque(Lbft)

1500 19.91 69.70
2000 28.49 74.81
2500 38.79 81.48
3000 51.83 90.73
3500 59.04 88.59
4000 66.93 87.88
4500 75.17 87.73
5000 82.03 86.17
5500 86.84 82.92
6000 86.49 75.71


Both these engine use the ACD - RS cam available from myself. This cam gives a smooth idle.

For more power figure verses engine specs as tested by myself look at the link;

http://www.mlmotorsp...opic,124.0.html



AC

Edited by ACDodd, 11 May 2012 - 09:10 PM.

[mini-luke]

Those are pretty impressive torque figures AC, certainly got me interested.

[ACDodd]

Modern cam profile makes the maximum use of the torque production capability of this engine type!

AC

[ACDodd]

http://img.photobuck...fts/Camlist.jpg


Its a bad image but if you zoom in you should be able to make it out. I also produce 2 other cams not listed. PM your email Addy and I'll send you some up to date bumf!!


AC

Edited by ACDodd, 11 May 2012 - 09:31 PM.