Wildcat Rover V8 making no power
Discussion
I've got a car on the rollers, running an Ian Richardson / Wildcat 5.3 Rover V8 with Wildcat stage 1 heads (whatever that means .. the head flows seemed to vary over the years it seems) and a Crane mechanical 256 cam according to the owner, 48mm individual throttle bodies and 4 into 1 exhausts of reasonably equal length around 24 inches from the flange to merge collector. So it's got (on paper) what would appear to be a good spec to make power.
The engine has made a pitiful 305hp and 330lb.ft guesstimated flywheel (ish .. dyno dynamics rolling road)
I was expecting well north of 400hp from the engine and 400lb.ft (5300cc x (say)75lb.ft/litre for a 2valver)
A few checks reveal ..
compression pressures on hot cranking are 165/170psi across all 8 cylinders so all very even but all much lower than I would expect. Engine was supposed to have 10.5:1 compression at build according to the owner. Surely over 200psi would be much more sensible?
A quick check on cam timing from a rocker through the oil filler hole showed 103deg .. owner says it was timed at 104 ... I can't find any specs for a crane M256 from a quick google this morning though (only a kent m256 .. same cam or owner confused? kent spec is 304deg in 310deg ex timed in at 104 from what I can gather) but it's not going to be far out at the 103/104ish it's set at right now.
I guess the question really is : from your experience engine builders, how much power is lost with an engine which is (seemingly) built with nowhere near enough compression ? Can it really be over 100hp down ?
One for the engine builders ... over to you.
The engine has made a pitiful 305hp and 330lb.ft guesstimated flywheel (ish .. dyno dynamics rolling road)
I was expecting well north of 400hp from the engine and 400lb.ft (5300cc x (say)75lb.ft/litre for a 2valver)
A few checks reveal ..
compression pressures on hot cranking are 165/170psi across all 8 cylinders so all very even but all much lower than I would expect. Engine was supposed to have 10.5:1 compression at build according to the owner. Surely over 200psi would be much more sensible?
A quick check on cam timing from a rocker through the oil filler hole showed 103deg .. owner says it was timed at 104 ... I can't find any specs for a crane M256 from a quick google this morning though (only a kent m256 .. same cam or owner confused? kent spec is 304deg in 310deg ex timed in at 104 from what I can gather) but it's not going to be far out at the 103/104ish it's set at right now.
I guess the question really is : from your experience engine builders, how much power is lost with an engine which is (seemingly) built with nowhere near enough compression ? Can it really be over 100hp down ?
One for the engine builders ... over to you.
Valve sizes, head flow in cfm would be handy, without which it's hard to say what a power potential is. The 256 is a big cam and would ideally want a lot more than 10.5:1 CR. Looking at my cranking pressure chart
https://web.archive.org/web/20110903073621/http://...
You wouldn't be expecting 200 psi from that combo even in good nick but it does look like the engine is a bit down from its best. I would suggest 11.5:1, a hone and a set of rings would help. Also check lift on each lobe in case you have a cam going south.
My best guess on how much power you're losing is about 15% so I'd say 350/360 bhp, high 300s ft lbs with the CR raised and the engine in good nick. Expecting over 400 bhp is probably pie in the sky. The claimed power outputs of the Rover V8 are usually very optimistic. The Rover head castings certainly never flowed enough no matter how much you modified them to give really big power. I couldn't speak as to aftermarket head castings if that's what this Wildcat thing is.
https://web.archive.org/web/20110903073621/http://...
You wouldn't be expecting 200 psi from that combo even in good nick but it does look like the engine is a bit down from its best. I would suggest 11.5:1, a hone and a set of rings would help. Also check lift on each lobe in case you have a cam going south.
My best guess on how much power you're losing is about 15% so I'd say 350/360 bhp, high 300s ft lbs with the CR raised and the engine in good nick. Expecting over 400 bhp is probably pie in the sky. The claimed power outputs of the Rover V8 are usually very optimistic. The Rover head castings certainly never flowed enough no matter how much you modified them to give really big power. I couldn't speak as to aftermarket head castings if that's what this Wildcat thing is.
Edited by Mignon on Monday 29th October 09:51
Thanks Dave .. I have asked the owner if he knows the head specs at all.
I will be pulling the rocker covers off to quickly check the relative valve openings later today.
Incidently I can't get the link in your post to work but I'm trying from my 'phone right now so might be the link not working on mobile .. will try later when back in the workshop.
I will be pulling the rocker covers off to quickly check the relative valve openings later today.
Incidently I can't get the link in your post to work but I'm trying from my 'phone right now so might be the link not working on mobile .. will try later when back in the workshop.
Looking at ACR's website the heads should have 49mm inlet valves and assuming they are designed well enough to flow proportionately then 400 bhp should certainly be on the cards. Rover castings can't be opened up enough to get more than a 43 mm inlet to flow decently and about 170 cfm is what I've seen from them. I'd expect 220 cfm or a bit more from 49 mm valves.
So yes you seem to be losing a lot more than just the CR and compression readings would indicate. On the bright side this should make it easy to find. A bunch of knackered cam lobes would certainly be one explanation.
So yes you seem to be losing a lot more than just the CR and compression readings would indicate. On the bright side this should make it easy to find. A bunch of knackered cam lobes would certainly be one explanation.
A couple more things. Check that the TB linkage system is giving full throttle. i.e. Butterflies fully open. It's a silly thing but it's been missed many times over the years. Exhaust sizing I would suggest needs to be 1 5/8" primaries, 1 7/8" secondaries and 2 1/4" to 2 3/8" system if it's twin pipes. 3 1/4" if it's a single pipe. There's nothing else I can think of that would lose 100 bhp easily. Maybe a very restrictive air filter.
spitfire4v8 said:
compression pressures on hot cranking are 165/170psi across all 8 cylinders so all very even but all much lower than I would expect. Engine was supposed to have 10.5:1 compression at build according to the owner. Surely over 200psi would be much more sensible?
Wouldn't the long cam reduce the compression readings?Indeed. And had it made decent power on those readings I'd have been happy .. but it's dreadful power al the way through and I wondered (not being an engine builder) how much of the power loss could be atributed to not having the compression high enough.
I know Dave has spoken in the past of over 200psi on his race engines, but I think the thread I was looking at was on 4v peugeot engines and I'm not sure how racey a race cam for 4v compares to a racey-ish cam for a 2valve Rover. 165/170 just seemed low anyway even for a performance engine ? But as I say I'm not an engine builder and have never needed to investigate compression pressure v power for a range of cams, so hoped some of the very knowledgable engine builders on here might have some answers.
I will be investigating the more physical aspects later eg full valve lift on all valves.
Throttles do open fully .. in fact getting the throttles in sync through their whole travel has been one of the tasks I've done .. the previous linkage was somewhat variable in ratio across the banks ...
will get on to it later.
Valves are apparently 49.2in 40.6ex
I know Dave has spoken in the past of over 200psi on his race engines, but I think the thread I was looking at was on 4v peugeot engines and I'm not sure how racey a race cam for 4v compares to a racey-ish cam for a 2valve Rover. 165/170 just seemed low anyway even for a performance engine ? But as I say I'm not an engine builder and have never needed to investigate compression pressure v power for a range of cams, so hoped some of the very knowledgable engine builders on here might have some answers.
I will be investigating the more physical aspects later eg full valve lift on all valves.
Throttles do open fully .. in fact getting the throttles in sync through their whole travel has been one of the tasks I've done .. the previous linkage was somewhat variable in ratio across the banks ...
will get on to it later.
Valves are apparently 49.2in 40.6ex
I like to see 200 psi on any N/A 2v engine and a bit more on 4v ones which are more resistant to detonation. You can go higher on high octane fuel but that should see you in the ballpark on pump petrol. Anything much less than 200 psi and you don't have enough CR for the cam duration and it's wasting power for no good reason.
I ran a griffith 500 with a few tuning bits and emerald ecu just before this wildcat car and it made 316hp, and it's a car I've known for 15 years so I know what to expect from it. I ran a chimaera 400 just after the wildcat and it made 246hp with a slightly peaky torque curve compared to a std 400 so probably had a better cam in it at some point (the engine has 105,000miles so could be on its third cam by now!) .. but pretty much what I'd expect .. so this wildcat engine really does look like it is down on power.
You also get a feel for what cars feel like on your own rollers .. normally with a large capacity (5 litres or more) rover V8 I'd have to do a few runs and get some heat in the tyres to eliminate wheel slip, and I'd feel the car really straining against the tie down straps .. but not with this wildcat engine. It gave me no wheel slip issues at all .. and didn't feel like it was straining against the straps during the full throttle runs either. Not a good sign.
I've just run down the valves with my verynear calipers .. a bit awkward to get on many of them because of the confines of the engine bay limiting how vertical I could get my calipers .. but the upshot is all valves measured between 13mm and 13.8mm lift.
The spec is 13.05in-13.56ex so they're bang on bearing in mind the limitations of my measuring attempt. I was hoping to find several with next to no lift, sadly this isn't the case.
There's a bit of exhaust near the back of the car which goes from large bore 3inch into 2 separate pipes, and the splitter doesn't look too great to the eye, so I will remove the rear section of exhaust and run a straight pipe out of the back of the car ..
but if it gets me another 100hp+ I'll be amazed!
So .. its got massive valves, opening at least 13mm from a cam that looks there or thereabouts timing wise. It's got massive ITBs opening fully and fed by generous radius bellmouths into open atmosphere so no filter restrictions, fed with cold (atmospheric ie not sky high temps) air on the dyno.
It's got big bore 4 into 1 exhaust manifolds just measured at 44mm o/d .. mappable ecu to get the fuel and ignition done, flow matched injectors, the plugs are all coloured up ie none running weak / glazed etc and the exhaust sounds nicely even under load too, no nasty weak mixture crackles and I'm running around 12.5:1 afr under load, but makes the same power slightly richer and weaker than this .. and 29 degrees advance at the top end as minimum best timing.
I've got the rocker cover breathers going to atmosphere so not contaminating the incoming air. The brakes aren't binding. etc etc
I feel I've given it it's best chance to make decent power!
The only thing (i think) that's relatively easy to check is to remove that rear exhaust section and run it up again but ...
anyway I'll let you all know what happens one way or the other!
You also get a feel for what cars feel like on your own rollers .. normally with a large capacity (5 litres or more) rover V8 I'd have to do a few runs and get some heat in the tyres to eliminate wheel slip, and I'd feel the car really straining against the tie down straps .. but not with this wildcat engine. It gave me no wheel slip issues at all .. and didn't feel like it was straining against the straps during the full throttle runs either. Not a good sign.
I've just run down the valves with my verynear calipers .. a bit awkward to get on many of them because of the confines of the engine bay limiting how vertical I could get my calipers .. but the upshot is all valves measured between 13mm and 13.8mm lift.
The spec is 13.05in-13.56ex so they're bang on bearing in mind the limitations of my measuring attempt. I was hoping to find several with next to no lift, sadly this isn't the case.
There's a bit of exhaust near the back of the car which goes from large bore 3inch into 2 separate pipes, and the splitter doesn't look too great to the eye, so I will remove the rear section of exhaust and run a straight pipe out of the back of the car ..
but if it gets me another 100hp+ I'll be amazed!
So .. its got massive valves, opening at least 13mm from a cam that looks there or thereabouts timing wise. It's got massive ITBs opening fully and fed by generous radius bellmouths into open atmosphere so no filter restrictions, fed with cold (atmospheric ie not sky high temps) air on the dyno.
It's got big bore 4 into 1 exhaust manifolds just measured at 44mm o/d .. mappable ecu to get the fuel and ignition done, flow matched injectors, the plugs are all coloured up ie none running weak / glazed etc and the exhaust sounds nicely even under load too, no nasty weak mixture crackles and I'm running around 12.5:1 afr under load, but makes the same power slightly richer and weaker than this .. and 29 degrees advance at the top end as minimum best timing.
I've got the rocker cover breathers going to atmosphere so not contaminating the incoming air. The brakes aren't binding. etc etc
I feel I've given it it's best chance to make decent power!
The only thing (i think) that's relatively easy to check is to remove that rear exhaust section and run it up again but ...
anyway I'll let you all know what happens one way or the other!
Looking at my notes from the runs the difference between the best run and one with 3 degrees taken out was only 5-6hp at best so 1.5-2 percent .. I don't know what you find with mapping rovers on your dyno Peter but with most rovers being fairly low compressions, and the breathing being somewhat limited on the rover head castings, that you can swing the timing an easy 3-4 degrees and make little impression on the top end figures anyway. 26 to 29 degrees to make 5hp doesn't seem particularly sensitive to ignition changes to me. No idea about highly tuned 4 valve engines though as I rarely see them so don't really have much experience on how power might change on a more sensitive engine ... Many aftermarket ecus allow you to trim ignition by fractions of a degree, I could get away with +/- 2 degree increments most of the time on the engines I see!
I will do a leakage test just as soon as I get back onto the car .. sadly it's overstayed its alloted time and now other booked in work is getting in the way. Should have more info at the end of the week though.
I will do a leakage test just as soon as I get back onto the car .. sadly it's overstayed its alloted time and now other booked in work is getting in the way. Should have more info at the end of the week though.
We usually find the higher cr engines are quite tight in terms of best advance. 1/2 to 1 degree differences seem to be the norm for a sharp engine. If we find the engines don't give a flying whatsit over 3 or 4 degrees and it is high cr comp-type engine then there is something wrong with the engine.Either internally such as knackered rings, cam timing, low cr, crap exhaust, etc etc.We have even had poor cam grinds!
99hjhm post reminds me we had a problem with some inserts on a 5.3 V8 with SD1 heads, the inserts were hammering up into the ports and power faded about 10 bhp per run!
99hjhm post reminds me we had a problem with some inserts on a 5.3 V8 with SD1 heads, the inserts were hammering up into the ports and power faded about 10 bhp per run!
Can’t go into to much detail as busy with work,
The flow data I have avaliable shows these heads will do 140cfm @10” quite easily with that valve size and lift. 96mm test bore. Some results are over 150 for well reworked heads on 100mm bore at .550” lift. So you would have to get it badly wrong. I didn’t record the data btw.
The flow data I have avaliable shows these heads will do 140cfm @10” quite easily with that valve size and lift. 96mm test bore. Some results are over 150 for well reworked heads on 100mm bore at .550” lift. So you would have to get it badly wrong. I didn’t record the data btw.
I think those old style heads will run 47/39mm valves. Witch are more sensible than ACR bigger ones..
I' m not fan of those old wild cat heads..
Like this costello engine..
https://www.mgcostello.com/the-ultimate-costello-v...
335hp witch is very boor..
If my 5.2l with home ported Rover heads give 418hp.. Those wild cat have to make at least 450hp with that cam..
Sounds stupid but port's are not ported enought? I have got pair ACR wild cat heads. And intake port's are small without porting..
I' m not fan of those old wild cat heads..
Like this costello engine..
https://www.mgcostello.com/the-ultimate-costello-v...
335hp witch is very boor..
If my 5.2l with home ported Rover heads give 418hp.. Those wild cat have to make at least 450hp with that cam..
Sounds stupid but port's are not ported enought? I have got pair ACR wild cat heads. And intake port's are small without porting..
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