Power output of Rover V8 5L engine

[CLINT887]

Could any of you tuners out there tell me the theoretical limit (BHP/torque) of this engine. The old yardstick used to be 100bhp per litre. Does this mean that this figureccould be achieved with a Chim 500 bearing in mind the old design of the engine.

[350matt]

Very much doubt this unless forced induction was used, even then you'd have to spend considerable amounts on the right /custom components to make it reliable.
This is why most upgrades are capacity increases as thats the easiest method of big power steps.

Matt

[IPAddis]

The yardstick of 100bhp/litre is usually obtained by making the engine rev very highly (small stroke) with a suitable camshaft to match (assuming natural aspiration). This creates excellent top end power at the sacrifice of low end torque.

Given the push-road design of the Rover V8 and the long stroke of the 5 litre versions, it is very difficult to obtain the same high revving characteristics. Whilst you can get some race versions of the engine to rev quite high, they are almost undriveable on the road and certainly not as nice to drive as a road version with a nice fat torque curve.

The Ferrari 355 has more power than a Griff 500 (close to 100bhp/litre) but the Griff puts out 300lb/ft of torque at 1500rpm where the Ferrari can only manage 288lb/ft at 6000rpm ish.

All IIRC.

Ian A.

[2 sheds]

Your more likely to achieve near to 100 per litre from a 3.5 but would need to rev to over 8000 rpm
a friend of mines runs an 3.5 SDI racer with over 325 bhp.
for road engines 70 per litre is about all you can achieve, otherwise you give away too much mid range torque.
Tim

[shpub]

Spend enough money and you can hit 400 bhp/400lb torque without sacrificing mid range although you wouldn't want to run it as a road car. The 520 has around 300 lb at 1800 revs but the power doesn't come in until 3000 rpm. Peak is at 6500 and the engine will rev to 7000 but we have a self imposed rev limit. John Eales reckoned that more power is possible but as it was wrecking suspension and transmission (now using tractor UJs to stand a chance of coping) I have turned down the next upgrade till next year.

Single fuel power consumption is an issue to start with. 1200 miles per set of rear tyres is another that comes to mind as well... Also upgrade everything else. Details in the 520 story on www.t-v-r-services.co.uk.

[boosted ls1]

100bhp per litre is a well know yardstick often bandied about but this may refer to engines with smaller bores and lots of revs. Am I right in thinking that engines with larger bores usually have a slower burn time and are basically less able to meet the 100 bhp per liter. Most big v8s seem to be low on bhp and I reckon this is one of the reasons? Now torque, thats another matter.

[350matt]

The main reason most big V-8s stuggle to produce big BHP numbers is poor cylinder head / port combustion chamber design. This allied to the fact that most of them are pushrods which always makes it more difficult to produce a decent cam design and combustion chamber for that matter. A modern 4-cam V8 ie BMW's 5.0ltr M lump now thats a different matter, howeve I think most of us would struggle to fit one of these under a TVR bonnet or between the chassis rails for that matter.
There are heads available for the Rover (wildcat?)which are supposed to be far superior to the stage I/III items but I've yet to talk to anybody about specific gains for them.

Matt

[grigio alloy]

My 5.2 litre Rover based V8-race spec from V8 Developments with (very expensive) Motec sequential fuel injection, full carbon kit, sport cat, (ally rad, uprated brakes and clutch etc etc) was bench dynoed at 377bhp at if I remember correctly around 6000rpm with peak torque of 400lbft at around 4800rpm. Without Motec it would have been undriveable.
Although I had many many probs with the engine it was awesome when it was on song. It revved cleanly to 7500rpm.
However the problems I had-high oil consumption, rocker cover leaks, sump leaks plus others cost me too much money and stress, so I was forced to sell.
From my experience more than 380bhp from a Rover based V8 (without forced induction)for a road application would not be feasible.
By the way for the Griff I think the chassis(and driver!) and aerodynamic limitations of the design were cruelly exposed by this engine altough I had 4 pot brakes etc

[2 sheds]

Just supplied V8 Developments some induction stuff for one of their new 5.3s they fitted a "soft"cam and on the bench dyno saw nearly 400 lb ft,& about 320 BHP this wasn't a very high spec engine either. the heads were regular ported rover type. the only problem with the bespoke heads is they tend to flow too much with not enough swirl, and swirl is what you need for torque.
I think with a decent cam V8s 5.3 would make 360 bhp and torque without going OTT with heads.
Tim

[MikeG]

I believe that the 100bhp standard typically refers to smaller engines than the old Rover V8. The capacity of an engine is related to cross sectional area of each bore multiplied by stroke (plus unswept vol), but the available space for fuel/air inlets is only normally related to the cross sectional area of each bore (fancy head designs excepted).

Therefore the space available for inlet valves does not increase in direct proportion to the increase in engine capacity. Fuel/air mixture velocity rates may already be close to their optimum for a normally aspirated engine delivering 100bhp/litre so there may not be much more scope to improve in this area for a bigger capacity engine. Perhaps this why a common complaint of the Rover V8 5 litre engine is that it can suffer from restricted induction at the top end of it's rev range.

Apologies for the simplistic view above but it helped me understand what I was trying to say.

Mike

[CLINT887]

Since posting the original query I have been on to the Puma Race Engines Technical Guide site where they give an intriguing "rule of thumb" guide to calculating peak power potential. First calculate total valve area then make a percentage adjustment for engine design this ranges from minus 10% for parallel valve 2 per cylinder to plus 25% for race engines.They then predict the flywheel bhp by dividing by 30 and finally take 75% of this for fast road tune and 85 to 90% for rally tune to get their final figure. On this basis they compare a 3.5/3.9 Rover V8 with a 1905cc Peugot 405 M16. The total valve area for the V8 with 40mm valves comes to 10,053 sq mm--reduce by 10% for engine design giving 9048sq mm then divide by 30 giving a target power max of 302 bhp so fast road would be 75% of this or 226bhp rally,at best,would be about 272 bhp. The wee Pug on the other hand with its better engine design has a target of 276 bhp (presumably at autobahn busting revs!). It is very interesting how relatively unimportant capacity alone is in these calculations

[dudfieldjp]

V8 Developments built me a 5.0 litre engine (based on the TVR Griff block and crank) which gave 321bhp at 5600rpm and 360lb.ft of torque at 3600 rpm. The engine had stage 3 heads and flapper injection (XJ6 based).

I am aware of a 'special' 5.0 litre producing just over 400bhp, but 500bhp would be difficult with the long stoke and 2 valves. Strap on some turbos and the limitations are less limiting.

[dudfieldjp]

Following on from my previous posting - I also had the ACT plenum, 45mm trumpet base, and its now in my 680kg Westfield.

The ACT plenum seems to find the extra torque. The torque is above 300lb.ft from 2400rpm to 5500rm and the power above 300bhp from 4500 to 6500rpm. The power was also 100bhp at 2200rpm.

[kevinday]

dudfieldjp said: Following on from my previous posting - I also had the ACT plenum, 45mm trumpet base, and its now in my 680kg Westfield.

That makes for a pretty awesome power to weight ratio.

[zob1]

2 sheds said: Just supplied V8 Developments some induction stuff for one of their new 5.3s they fitted a "soft"cam and on the bench dyno saw nearly 400 lb ft,& about 320 BHP this wasn't a very high spec engine either. the heads were regular ported rover type. the only problem with the bespoke heads is they tend to flow too much with not enough swirl, and swirl is what you need for torque.
I think with a decent cam V8s 5.3 would make 360 bhp and torque without going OTT with heads.
Tim

Well Tim, it seems you are talking about my engine : 5.3 Hotwire, Adams ECU, ACT Triple. Results on the Dyno are 400 lbft @ 3600, 320 bhp @ 4600 and at least 300hp between 4000 and 5600 rpm. Using my Griff on a daily basis during summer time, driveability was more important for me than pure peak power (even if I was expecting a little bit more bhp). To be honest I asked myself for a soft cam (Switzerland has although some tough smog regulation and I didn't wanted having too much cross-talk timing between input and output valves).

By the way I would be interested talking to you because I have some suggestions not on the design or performances of your products but more on the mounting quality of your components : I had to ask my dealer to eliminate some obstructing residual glue and rubber in the trumpets, and there are small cracks on the air box where the air-flow is mounted inducing a probable air leaking (this is certainly due to the metal collar directly mounted on the carbon surface)

Regards

JC Emery

[2 sheds]

zob1 said:

2 sheds said: Just supplied V8 Developments some induction stuff for one of their new 5.3s they fitted a "soft"cam and on the bench dyno saw nearly 400 lb ft,& about 320 BHP this wasn't a very high spec engine either. the heads were regular ported rover type. the only problem with the bespoke heads is they tend to flow too much with not enough swirl, and swirl is what you need for torque.
I think with a decent cam V8s 5.3 would make 360 bhp and torque without going OTT with heads.
Tim

Well Tim, it seems you are talking about my engine : 5.3 Hotwire, Adams ECU, ACT Triple. Results on the Dyno are 400 lbft @ 3600, 320 bhp @ 4600 and at least 300hp between 4000 and 5600 rpm. Using my Griff on a daily basis during summer time, driveability was more important for me than pure peak power (even if I was expecting a little bit more bhp). To be honest I asked myself for a soft cam (Switzerland has although some tough smog regulation and I didn't wanted having too much cross-talk timing between input and output valves).

By the way I would be interested talking to you because I have some suggestions not on the design or performances of your products but more on the mounting quality of your components : I had to ask my dealer to eliminate some obstructing residual glue and rubber in the trumpets, and there are small cracks on the air box where the air-flow is mounted inducing a probable air leaking (this is certainly due to the metal collar directly mounted on the carbon surface)

Regards

JC Emery

The problems you mention are nothing to do with me, and occur during fitting , of which i was not involved,

Chris phoned me just after test driving your car, he was still laughing about the monstrous performance.

Tim



>> Edited by 2 sheds on Saturday 8th February 20:41

[zob1]

2 sheds said:

zob1 said:

2 sheds said: Just supplied V8 Developments some induction stuff for one of their new 5©3s they fitted a "soft"cam and on the bench dyno saw nearly 400 lb ft,& about 320 BHP this wasn't a very high spec engine either© the heads were regular ported rover type© the only problem with the bespoke heads is they tend to flow too much with not enough swirl, and swirl is what you need for torque©
I think with a decent cam V8s 5©3 would make 360 bhp and torque without going OTT with heads©
Tim

Well Tim, it seems you are talking about my engine : 5©3 Hotwire, Adams ECU, ACT Triple© Results on the Dyno are 400 lbft @ 3600, 320 bhp @ 4600 and at least 300hp between 4000 and 5600 rpm© Using my Griff on a daily basis during summer time, driveability was more important for me than pure peak power ¥even if I was expecting a little bit more bhp¤© To be honest I asked myself for a soft cam ¥Switzerland has although some tough smog regulation and I didn't wanted having too much cross-talk timing between input and output valves¤©

By the way I would be interested talking to you because I have some suggestions not on the design or performances of your products but more on the mounting quality of your components : I had to ask my dealer to eliminate some obstructing residual glue and rubber in the trumpets, and there are small cracks on the air box where the air-flow is mounted inducing a probable air leaking ¥this is certainly due to the metal collar directly mounted on the carbon surface¤

Regards

JC Emery

The problems you mention are nothing to do with me, and occur during fitting , of which i was not involved,

Chris phoned me just after test driving your car, he was still laughing about the monstrous performance©

Tim



>> Edited by 2 sheds on Saturday 8th February 20:41

Hello Tim,

Well in that case there is a second guy who ordered a 5©3 engine with an ACT Intake© Chris already told be about the performances so I guess that I will be quite happy in a few days¥My engine just arrived yesterday in Switzerland and is still not mounted¤© Regarding the fitting problems I will forward my remarks to Chris©

Regards

JC