Speed Six Rebuild: Power 4.3 or 4.5?

[The Pits]

My car produced 326bhp at the wheels on Dom's dyno. That works out at 375bhp at the fly, which is almost exactly what a 4.0 S should do. Certainly no gross exaggerations or fiddling the figures going on at TVR Power in my experience.

The factory revised their power claims downwards to 375 from 400 towards the end. I guess nudging 380 was too close to 400 for the marketeers to resist and to his credit Smolenski (either initiated it or agreed to it) decided to set the record straight.

375bhp is plenty for an 1100kg car. Hence the way it tears down the road like its pants were on fire.

[Speed eight]

To answer the previous question.

My engine has been tested on an Industry Standard engine dyno. At John Sleath Race Engines.
A Land and Sea engine dyno. Further more this particular dyno has been back to back tested with the Superflow 900 dyno at EDA and shows within 2hp identical figures. Safe to say that my power is genuine.
I have posted up the graph for all to see........
This is real, no fudge factor at all.

I am happy to put my Tuscan onto a Dynojet Research RR.
This will give a definitive result.
These RR always, always show inflated figures at the wheels. Of that there is no question.

I have worked and lived in the USofA and can tell you this.
The Land and Sea engine dyno is used by hard core race engine builders. Winners of many race series events.
The Dynojet is used by custom engine builders to sell engines.


Regards.
Speed eight.

[Mattt]

D14 AYS said:

jcpgasoline said:

RedSpike66 said:

With all these engines being taken out for a full rebuild 4.3, 4.5, FFF why has no-one bothered to put one on a proper engine dyno to get the real figures once and for all and stop all this willy waving ???

Every time a graph gets posted it's the same old same old arguments (of which I for one am really bored now)

There must be at least one engine dyno in the country accessible to the 'public' ?

If I ever get (or need) my engine re-built, I vow to put it on an engine dyno (if accessible and I can afford it !)

I intend to do exactly this when I get my car back and it has been run-in and mapped...

+1 ...... here http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Engine dyno, not rolling road.

I know of a Piper engine dyno for sale in Essex if anyone fancies it.

[m3jappa]

I really don't think these cars want too much power, i think they would be undriveable.

Mine is a freshly rebuilt 4 ltr, meant to be a red rose but who knows?

Lets say that it goes well, very driveable now it has got trackday tyres on it and a proper geometry set up, raised rack and gold pros.

Even with those tyres it spins through first and second, any more power would be pointless unless your talking 120mph + which imo is an area not worth going on the roads at least.

Theres a surge of power around 5.5k ish and really feels like its run out by just over 7k. This is one of the only cars ive driven where its not hit the limiter, it just feels that last bit to hit it is a struggle so i dont bother at all.

I would love a 4.3 or 4.5 and when mine was rebuilt by dom i was offered the upgrade which i declined as it was too much for me to throw at a car i feel has very good power anyway.

Maybe in a 350 or sag i would as they are a bit heavier and the exhausts i believe hinder the standard engine meaning it wont make as much as the tuscan anyway.

I would like to try a 3.91 diff though (mine is 3.73) as i think it would make 3rd a bit more useable as at times your too slow in 3rd for proper power but too fast to drop into second without dropping to 6k rpm.

[dpd3047]

Totaly agree S8, lets look at the standard engine specs for 3.6 and 4.0 litre they have all the same parts head, cams, block injection system and ancillaries the only difference is the stroke so crank, rods, and pistons and engine map are different copmression on both engines is 11 to 1 nominal, red rose S and sagaris
have higher compression 11.5 to 1 , different cam timing but the cams are the same and remap so where are all these big numbers coming from to much bench racing me thinks the only rolling road i respect the numbers on is a dynodynamics set up correctly the actual power figures for the engines are.
3.6 335@ 7000 rpm torque 290 ft lbs
4.0 342@ 6500 rpm 298 ft lbs
Red rose 362 @6800 rpm 300 ft lbs
S 364 @ 6800 rpm 300 ft lbs
sagaris 362 @ 6800 rpm 300 ft lbs
these are flywheel BHP figures you will get slight variations of a few BHP ether way

Edited by dpd3047 on Tuesday 28th June 20:42

[RedSpike66]

Hi dpd3047,

I'm presuming you worked at the factory or on TVR SP6 engine testing somewhere to have such accurate information - first time I have seen it in the 5 years I've been on here. Thanks.

Engine dyno figures from any of the upgrades would be really informative for all current and future/prospective purchasers...

One likes to know what one gets for ones money !

SpeedEight,

Can anyone have their engine tested at John Sleath's place ?

[Vixpy1]

Mattt said:

Engine dyno, not rolling road.

I know of a Piper engine dyno for sale in Essex if anyone fancies it.

Half the bloody world has tried to flog me that dyno in the last few weeks

[The Pits]

My car has 200 cell cats and a remap so again, 375 at the flywheel sounds about right.

[Gazzab]

dpd3047 said:

Totaly agree S8, lets look at the standard engine specs for 3.6 and 4.0 litre they have all the same parts head, cams, block injection system and ancillaries the only difference is the stroke so crank, rods, and pistons and engine map are different copmression on both engines is 11 to 1 nominal, red rose S and sagaris
have higher compression 11.5 to 1 , different cam timing but the cams are the same and remap so where are all these big numbers coming from to much bench racing me thinks the only rolling road i respect the numbers on is a dynodynamics set up correctly the actual power figures for the engines are.
3.6 335@ 7000 rpm torque 290 ft lbs
4.0 342@ 6500 rpm 298 ft lbs
Red rose 362 @6800 rpm 300 ft lbs
S 364 @ 6800 rpm 300 ft lbs
sagaris 362 @ 6800 rpm 300 ft lbs
these are flywheel BHP figures you will get slight variations of a few BHP ether way

Edited by dpd3047 on Tuesday 28th June 20:42

Interesting numbers....the numbers that one would expect from a S6. So how does adding 500cc gain such massive bhp (where TVR got only 29 extra).

[dvs_dave]

TVR Power standard 4.0S rebuild. 361bhp/7230rpm, 285lb-ft/5470rpm at the Hubs.

Assuming 9% transmission losses that's 397 bhp at the fly.



BMEP of 178.5 psi so bang inline with the theory. So basically you all need to stop being girls and rev them properly as that's where the properly built engines make their power!

[spitfire4v8]

.. and yet when I tested your car it didn't make anything even remotely close to 397hp .. more like 350hp. Funny how people only believe the highest number they've ever been given ..

[DonkeyApple]

RedSpike66 said:

With all these engines being taken out for a full rebuild 4.3, 4.5, FFF why has no-one bothered to put one on a proper engine dyno to get the real figures once and for all and stop all this willy waving ???

Every time a graph gets posted it's the same old same old arguments (of which I for one am really bored now)

There must be at least one engine dyno in the country accessible to the 'public' ?

If I ever get (or need) my engine re-built, I vow to put it on an engine dyno (if accessible and I can afford it !)

It's a combination of marketing by the companies along with some slightly dubious tactics. Plus the simple fact that once an owner has spent that amount of money they don't really want to know the truth.

Either no rebuilds have been on RRs or they have and the owners are keeping quiet would be the more logical take on the situation.

As far as I am concerned, I will work on the assumption that it is mostly smoke and mirrors between all the firms and they have no real incentive to have core facts revealed independently. And enough of the owners of the engines would be out there showing their numbers if they were up where we have been talking on this thread.

I'm yet to be convinced that any type of s6 engine is breaking 100 bhp/litre.

[Speed eight]

Hello RedSpike66.
Anyone can use John Sleath Race Engines...........call John on 01709 862075.

Apart from winning almost every drag racing series over the years...........
He owns and runs the fastest street legal car in Europe. The first car to run180Mph on pump gas in under 7 seconds
So he knows what he is doing I think.

Look, lets forget about RR. It HAS to be engine dyno first. To establish a base figure. Then RR and the type of RR has to be understood.
I do not want to sound all knowing, because I am not. But there are different types of RR that read the HP in different ways.
Have a talk with engine builders or Google for the information.

As for revving the Speed Six engine. OK.
Let us look at the maths.
If the 4.3 or 4.5 Six, which has a rod ratio of 1.43 is taken to 7250Rpm then the piston speed reaches 78.5Ft/sec............ do you realise just how fast this is?
A formula one car at 18000Rpm has a piston speed of 80Ft/sec......... I ask, is this good for piston life?

I ask these questions as an Engineer. Not because I am trying to put down any ones work. I just like to understand things.
And try to find out why the Six is allegedly making 0.111 HP/cc. But I can only make 0.0841HP/cc as can John Sleath.
I know that the engines are different, but this is a massive shift.


Regards.
Speed eight.

[dvs_dave]

Actually the one and only time it's been on your dyno it "only" did 360, yet it was still the most powerful Speed Six on the day by a good margin and it also put a fair few AJPs to shame.....go figure.

Funny how all dyno operators believe that their dyno is the most accurate in the world and that everyone else's is useless. Have you ever seen TDI's dyno cell?

Willy waving and fanny flapping aside, 6250 rpm for max power is 1000rpm off when an S spec engine is doing it's best.

[dvs_dave]

Speed eight said:

Piston speeds.....

I've said it before but the Honda S2000 piston speeds are much higher so it's nothing special. F1 engines have a tiny stroke so they can do huge rpms without bonkers piston speeds, so again nothing special.

[dpd3047]

You have consider the mass now i know that at 7000 rpm the load on an s6 piston is 3.5 tons thats from AM himself thats why the engine suffers from torsional vibration, tvr fitted the fluid damper to try and cut down on this, the 4 litre suffers more than the 3.6 engine because of the longer stroke if you incease the stroke you increase friction, heat, piston speed, and torsional vibration.The big problem with the 4.0 litre is the conrod which the small end is heavier than the big end by 2grms that is engineering madness and as for the main caps two studs and just a locater dowel no wonder the caps walk and liners move.

[DonkeyApple]

dvs_dave said:

I'm a Luddite when it comes to these things but I remember having to infer meaning from charts as part of Maths GCSE.

Does that chart not imply that although you get a peak of 360BHP the ability to apply that horse power has been tailing off from nearly 2000 RPM earlier?

Can someone bring me up to speed on whether I am seeing this correctly?

[jcpgasoline]

DonkeyApple said:

I'm a Luddite when it comes to these things but I remember having to infer meaning from charts as part of Maths GCSE.

Does that chart not imply that although you get a peak of 360BHP the ability to apply that horse power has been tailing off from nearly 2000 RPM earlier?

Can someone bring me up to speed on whether I am seeing this correctly?

The "tailing off" as you put it is in the torque curve. But power is the mathematical product of torque and revs, so as long as revs increase faster than torque decreases, the engine will continue to generate more power at higher revs. So, even though peak torque was generated at about 5500rpm and declines thereafter, the engine speed increases faster which results in increasing power. On the other hand, you'll see from the graph that power starts to decrease after about 7250rpm, which is when the torque decreases faster than the revs climb.

[JR]

jcpgasoline said:

DonkeyApple said:

I'm a Luddite when it comes to these things but I remember having to infer meaning from charts as part of Maths GCSE.

Does that chart not imply that although you get a peak of 360BHP the ability to apply that horse power has been tailing off from nearly 2000 RPM earlier?

Can someone bring me up to speed on whether I am seeing this correctly?

The "tailing off" as you put it is in the torque curve. But power is the mathematical product of torque and revs, so as long as revs increase faster than torque decreases, the engine will continue to generate more power at higher revs. So, even though peak torque was generated at about 5500rpm and declines thereafter, the engine speed increases faster which results in increasing power. On the other hand, you'll see from the graph that power starts to decrease after about 7250rpm, which is when the torque decreases faster than the revs climb.

Quite so but the main thing about that graph is that the torque value only varies by about 10% across the whole of the rev range so "ability to apply that horse power" as you put it hardly changes at all. A very impressive graph.

[dpd3047]

Engine dyno`s measure torque its then converted into bhp, but some rolling roads measure bhp and convert this into torque these are inertia type DynaJet for one, the other type is steady state these measure torque and convert to bhp thats the one i would trust if set up correctly as a dynodynamics,torque is what makes the car move, if you use big cams in an engine you cant pull away at low revs as there is not enough torque to move the car look at and F1 engine that has to rev at 12000 rpm to pull away and it has around 200 ft lbs of torque at 18000 rpm but makes 720 bhp.