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Is there a noticeable difference with 9.0 :1 compression ?
Posted: Mon Apr 03, 2017 12:48 am
by Mick Boon
I took my Lomax for another test drive today it's almost flat out at 72 mph.... Is that about normal ? The engine is very sweet, just slow. Would new 9.0: 1 pistons give it more zip ?
Any good tuning tips would be appreciated.
Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Mon Apr 03, 2017 12:49 am
by Mick Boon
Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Mon Apr 03, 2017 11:01 pm
by kawlomax223
Sounds about right to me. I'm guessing that 72 mph was on the level? Remember the 2CV would just about do that... on a good day, with a following wind! Although several times I did get my 2CV 'off the clock'! Do you have a rev counter fitted? I'm thinking that at 72mph it'll be about 6500 rpm... just about max. So, just enjoy cruising, it's not just about top speed. IMO!

Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Tue Apr 04, 2017 6:06 am
by Mick Boon
There was a moderate wind from the side and it was on the flat, and two up. Yes I have a rev counter, and I think it was just under 6500 rpm. All is normal then

It's very happy at 60mph
Thanks !
Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Tue Apr 04, 2017 10:59 am
by Ken Hanna
Peak power of a standard 602 engine is at 5,750rpm, for both 8.5:1 & 9.0:1 compression ratios.
That engine speed corresponds to 72mph if the gearbox has 2CV ratios, 76mph with Dyane/Ami ratios and with tyres having an effective circumference under load of 1.842 metres.
Recommended peak rpm is 6,000 for engine longevity...

Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Tue Apr 04, 2017 12:40 pm
by billdavies
Mike,
Reading this post I see that you have a Lomax so there is a chassis member that you can use to support the Guzzi engine if you go that route.
Part of the reason that you only achieve 70 mph is your pointing the guns forwards, point them over your shoulder and the reaction will increase the terminal velocity...lol
Bill
Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Tue Apr 04, 2017 2:21 pm
by Mick Boon
billdavies wrote: ↑Tue Apr 04, 2017 12:40 pm
Mike,
Reading this post I see that you have a Lomax so there is a chassis member that you can use to support the Guzzi engine if you go that route.
Part of the reason that you only achieve 70 mph is your pointing the guns forwards, point them over your shoulder and the reaction will increase the terminal velocity...lol
Bill
Hi Bill, I just replied to your comment on the Pembleton forum, take a look

Re: Is there a noticeable difference with 9.0 :1 compression ?
Posted: Tue Apr 04, 2017 2:26 pm
by Mick Boon
Ken Hanna wrote: ↑Tue Apr 04, 2017 10:59 am
Peak power of a standard 602 engine is at 5,750rpm, for both 8.5:1 & 9.0:1 compression ratios.
That engine speed corresponds to 72mph if the gearbox has 2CV ratios, 76mph with Dyane/Ami ratios and with tyres having an effective circumference under load of 1.842 metres.
Recommended peak rpm is 6,000 for engine longevity...
I bought it as a 1963 Ami Lomax, but the only things that are from 1963 is the fuse box and the riveted on chassis plate number. Research has confirmed that the engine and gearbox is 2cv, and the chassis is a replacement..... I was only thrashing it so I could see what it could do honest
