Running cold/low mpg - what's the possible damage?

[roseytvr]

Ok I will try to be brief:

New engine built by well known specialist last year, approx 3000 miles done. Fully mapped and running a treat. Have only been getting 17 miles to the gallon on average but throttle bodies etc and some 360bhp I was told it was probably my right foot and if I wanted high mpg a modded rv8 ain't for me!

I had noticed the car was running cold on cruise, some 60 degrees but put it down to tvr gauges! How very wrong I was!

No thermostat fitted! Fitted new stat of the weekend and instantly up to 25 mpg and car running at 82 degrees! That's almost a 50% improvement in fuel economy FFS!

Anyhoo - what damage may I have done and what do I need to check? I have changed the plugs and will change the oil and filter this week. I am guessing I need to check the compression in case of bore wear - anything else I need to do? Apart from abusing "specialist" of course!

[NWTony]

Just to start the ball rolling, as long as it was mapped without a thermostat then it should be OK? The oil temperature and coolant temperature are two different things so I'd think damage was minimal to the engine.

I bet someone better informed corrects me shortly.

[carsy]

If the engine feels fine i suspect it will be. Go back to the rolling road for a quick power run. If bhp is still good and your not using oil, job should be a goodun.

Or like has been suggested a leak down test.

[neal1980]

Can you use the word specialist..I mean they forgot the thermostat!

Will be fine but still what a stupid mistake.

[V8 Fettler]

Belt and braces = change the engine oil in case it's contaminated by petrol washing down the bores. A long run at full oil temperature will achieve similar.

[EGB]

Compression for me at 56,000 miles was 170.3psi average. All satis in the Gunson green area.

[JamesMK]

I had the exact same problem after an engine rebuild by a well known specialist too.

Running cold, only achieving mid-teens mpg and a tendency to stall at low speeds. Turned out to have no thermostat fitted, a faulty throttle position sensor and in need of a complete re-map (among other issues which surfaced one by one). Once put right it runs far more willingly throughout the range and returns mid-twenties mpg. Took four other well known specialists to get this far though.

[roseytvr]

Thanks guys, spoke with Dom at TVR Power today and he has basically said what you guys have, it's not burning oil and he has offered to have a listen to it but whilst he is happy to do a leak down he doesn't think it will need one. I can't believe it took me 12 months to work this out, hey ho

[phazed]

First thing tomorrow I'm gonna check mine!

[Andy JB]

It was fairly common on RV8's to run without thermostat due to hot running especially in warmer climes.

Shouldn't cause engine damage often reverse in certain hot climates. As said if no oil burning should all be okay. I guess engine was overfuelling hence poor mpg

[phazed]

phazed said:

First thing tomorrow I'm gonna check mine!

Checked, all present and correct!