race engines "refreshing" what is it and why is it needed?
Discussion
This is just out of interest. It is often said that after a season a race-tuned, production-based engine needs a "refresh". I asume this means a strip and check, with replacement of things like shells etc. I'm interested in why they are needed, is it because the engine is worked so hard or because of the way they are put together in the first place? Obviously an engine that is used to, say, 9000rpm all the time and making lots of power is going to wear more than a road engine that only very occasionally sees 6000rpm but if you drove the race engine at 2-4000rpm, like a road car, would the bearings last for 100,000 miles like they do in a road car? If not, why not?
Thanks
Thanks
We refresh ours simply because it's easier to spend a little to prevent spending a lot!! We have a Rover V8, 3.9ltr full race spec making about 380bhp at the fly. It only ever gets driven in anger, gets oil changed every 2-3 rounds (which is a qually and 2 races per round), tappets checked/adjusted before every meeting and generally refreshed every other season (assuming it's done a full season). People often say we over-maintain though it's the old saying here - All the P's... (P... Poor Preparation Promotes P... Poor Performance) 
I've always thought of it as more of a strip/check operation. Often the only parts replaces are gaskets and seals, while the head is decoked and the valve seats are checked for a proper seal.
Usually a head refresh is an opportunity to check components and perform additional work as necessary.
Usually a head refresh is an opportunity to check components and perform additional work as necessary.
Shoestringracer said:
Obviously an engine that is used to, say, 9000rpm all the time and making lots of power is going to wear more than a road engine that only very occasionally sees 6000rpm but if you drove the race engine at 2-4000rpm, like a road car, would the bearings last for 100,000 miles like they do in a road car? If not, why not?
Mine wouldn't I suspect, it's built with clearances that don't need 500 miles of gentle running in before giving it some stick. It needed about one practice run to loosen up (couple of miles) and the chap that built it told me to give it full beans right from the start. Somehow I don't see it making 100,000 miles when it's built that loose to start with.I had to be more careful with the transaxle when I replaced that, spent a couple of hours pootling around Llandow after I installed it, on the advice of the person that put it together.
you refresh race engines because you are looking for 100% reliability and every ounce of perfromance from them. this means swapping shells, checking crank for wear etc as well as honing bores, measuring cam lift, decoking heads, re lapping valves in etc etc. As has already been said spend a little to try and avoid big bills. there does come a time though when you have to scrap blocks off as the ring gap becomes excessive for example.
Why do people think you need to change oil every meeting or so I dont get that one to be honest especially if running synthetics, I even put the question by the Oilman and failed to get a satisfactory answer. I run the chevies on full synthetic and change oils once a season and still see 70 psi hot on 5/30 weight oil. Surely if a reps car in and out of traffic and banging up and down the motorway is good for what 15 or 20,000 miles between oil and filter change a few sprint laps around a circuit isnt going to harm it. I had a small block chevy engine once for 4 seasons and bought off a mate who had it for two and I recon it would still be running today without a rebuild if I hadnt lent it to some cock who was desparate as he had sold a drive in his car and had left his engine through the winter with no anti-freeze (like I said a cock)and while his man was driving it, it through a fan belt as it left the pit lane but he just carried on driving it regardless till it cried enough!
Al, we change the oil very regular (I know it sounds like overmaintenance, but rather that than not doing it and getting a big bill!!). It allows you to inspect the oil and filter to ensure there are no metallic bits or other nasties that won't necessarily effect oil pressure until too late... Some people I know don't change the oil very regular at all - once a season if lucky and have no problems. I also know others who do the same and have had big problems!!
A reps car won't be getting driven flat out from cold, took to the red line time after time and generally thrashed like a race car would either (plus they ain't built for ultimate performance like a race engine would be).
Just my thoughts anyway...
A reps car won't be getting driven flat out from cold, took to the red line time after time and generally thrashed like a race car would either (plus they ain't built for ultimate performance like a race engine would be).
Just my thoughts anyway...
A refresh.
Because you are always looking for 100% and you are often pushing the boundaries of what the engine is capable of.
a refresh would nomally include things like re lapping valves in possibly re ringing basically going through the top end (the piano as i once heard it affectionally called) to check all clearances and basicallyy check alll the critical componants and their clearances. these are the bits that work the hardest and show wear first. 96% in your road car is no big issue. but there is little point throwing money (we all do) at marginal edges in performance if the basics aren't right. hence the refresh..
Because you are always looking for 100% and you are often pushing the boundaries of what the engine is capable of.
a refresh would nomally include things like re lapping valves in possibly re ringing basically going through the top end (the piano as i once heard it affectionally called) to check all clearances and basicallyy check alll the critical componants and their clearances. these are the bits that work the hardest and show wear first. 96% in your road car is no big issue. but there is little point throwing money (we all do) at marginal edges in performance if the basics aren't right. hence the refresh..
HustleRussell said:
I've always thought of it as more of a strip/check operation. Often the only parts replaces are gaskets and seals, while the head is decoked and the valve seats are checked for a proper seal.
Usually a head refresh is an opportunity to check components and perform additional work as necessary.
err..noUsually a head refresh is an opportunity to check components and perform additional work as necessary.
engine freshen should involve replacement of all wearing parts, ie. bearings, rings, seals etc.
Also, components like pistons etc have finite lives, road cars used cast pistons, these last for years, race spec forged ones don't.
Scuffers said:
HustleRussell said:
I've always thought of it as more of a strip/check operation. Often the only parts replaces are gaskets and seals, while the head is decoked and the valve seats are checked for a proper seal.
Usually a head refresh is an opportunity to check components and perform additional work as necessary.
err..noUsually a head refresh is an opportunity to check components and perform additional work as necessary.
engine freshen should involve replacement of all wearing parts, ie. bearings, rings, seals etc.
Also, components like pistons etc have finite lives, road cars used cast pistons, these last for years, race spec forged ones don't.
It depends on what state of tune you are talking about for a race engine, if the motors full of titanium valve gear it will need alot more looking after than the same motor with noramal stuff, prevention is better than cure, with most race motors they get alot of bore wash when they are cold, which means some petrol end up in the sump & for that reason alown I change the oil every couple of meetings
I think fancy oil all season without a change isnt as good as regular oil changed with 'good but not pants down priced oil' regualary changed
Regular compession checks & or leak down check are a good idea
I think fancy oil all season without a change isnt as good as regular oil changed with 'good but not pants down priced oil' regualary changed
Regular compession checks & or leak down check are a good idea
A full "refresh" is usually ends/mains/rings. Though it depends on the spec of the engine.
A hot hatch will benefit from a refresh every 300 races or so!!
A 740hp 2.4L Cosworth YB will want a refresh avery 6 racing hours - and that will probably include pistons/rods and maybe the crank!!
My 700hp 403ci Chevy needs (should need) a "refresh" every 48 racing hours, that's every other season in real terms. That would be ends/mains/rings.
My 430hp 350ci LS1 Chevy needs a refresh about the same. Every two years to keep it tip top.
My little 1600cc Nova had a refresh every season, though there was never any wear in anything when I did it last.
That's about 16hrs of use - qually/racing/testing.
I used to change the oil in the Nova every three meetings, or every other one if I went testing in-between.
Remember - oil is cheaper than engines.
A hot hatch will benefit from a refresh every 300 races or so!!
A 740hp 2.4L Cosworth YB will want a refresh avery 6 racing hours - and that will probably include pistons/rods and maybe the crank!!
My 700hp 403ci Chevy needs (should need) a "refresh" every 48 racing hours, that's every other season in real terms. That would be ends/mains/rings.
My 430hp 350ci LS1 Chevy needs a refresh about the same. Every two years to keep it tip top.
My little 1600cc Nova had a refresh every season, though there was never any wear in anything when I did it last.
That's about 16hrs of use - qually/racing/testing.
I used to change the oil in the Nova every three meetings, or every other one if I went testing in-between.
Remember - oil is cheaper than engines.
Still doesnt answere WHY you need to change the oil every three meetings, just what is the point, it would be a sad reflection on the manufacturers prodcut if it really needed changing at less than every 100 miles even if fully synthetic. Sorry just overkill and I dont buy it. Just started my engine this morning and it had 95 psi on 5/40 fully synthetic and 70psi when I left the track after 40 minutes hard running and the oil is as clean as when I put it in. If it is a concern for you fit an in line tattertale device which you can check after the race for any debris and save the costs in oil and filter, I have one at home somewhere its an American thing used on aircraft.
Edited by Al Weyman on Wednesday 6th June 12:56
Once I saw the oil turning beyond "golden" towards "yuk", I changed it. In the early days of the 1600 engine, the EFI system wasn't very sophisticated and dumped fuel in mid-range - which didn't help.
I had tried various oils over the years, Valvoline Racing 15/40 went black after one meeting!! Dirty filthy stuff.
Mobil-1 5/30 was the best stuff I ever used at that time. These days you can get better oil from just about anywhere.
The other thing to consider Al - it was a Super Road Saloon... road miles!! As it was MOT'd, it was taxed and insured - so used!! When it was a 1300 I still used it for work - doing 150 road miles a week!!
The Belmont, got a sludge change every 8 hours of running, thereabouts. That was running Valvoline VR1 20/50 then, but I've changed to a 5/30 synthetic now, so will see how it goes.
I had tried various oils over the years, Valvoline Racing 15/40 went black after one meeting!! Dirty filthy stuff.
Mobil-1 5/30 was the best stuff I ever used at that time. These days you can get better oil from just about anywhere.
The other thing to consider Al - it was a Super Road Saloon... road miles!! As it was MOT'd, it was taxed and insured - so used!! When it was a 1300 I still used it for work - doing 150 road miles a week!!
The Belmont, got a sludge change every 8 hours of running, thereabouts. That was running Valvoline VR1 20/50 then, but I've changed to a 5/30 synthetic now, so will see how it goes.
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