Speed Six Rebuild: Power 4.3 or 4.5?

[jcpgasoline]

Opinions please!

[jcpgasoline]

Well, it's always a consideration. I just want to get a feel for the relative merits & characteristics of each package...

[jcpgasoline]

Yes, I have considered it. I came to the conclusion that I must be something of a purist as I want to keep the finger followers. The 5 year warranty came in to it, too. Not sure about Syvecs, though.

[jcpgasoline]

Well, to be fair the Morgan does have a truck engine...

[jcpgasoline]

SAGRIFF said:

A few years ago I would have gone the LS route just because of reliability and torque issues even though I would have hated ripping out the TVR Speed Six.

But today if my engine went pop there is only one engine I would replace it with



a 4.5 TVR Power engine that now has reliability and a 5 year warranty and loads more torque and now is race proven with 2 wins in the GT Cup where it's quicker than the V8 F430GTC, V8 M3GTR and 997 GT3 Cups.

That's quite compelling...

[jcpgasoline]

Well, I'm convinced. 4.5 it is. Any idea how much torque & how many ponies I should expect from a de-catted 4.5 with ACT Airbox (incl trumpets)?

[jcpgasoline]

Speed eight said:

Just a moment......stop the bus!
Below is a typical 4.0Lt standard Six motor................





This gives a BMEP as follows.

HP x Constant (13000) / Litres x Rpm. =

345 x 13000 / 4 x 6250 =

4485000 / 25000 = BMEP of 179........ this is equivalent to the very best production engines
So you can see already how good 179 is.



Now if you are going to take a 4.5 to the 500Hp mark let us look at that equation.

500 x 13000 / 4.5 x 6250 =

6500000 / 28125 = BMEP of 231............ That is formula balls out racing specs !

A) Is this really possible for the Speed Six engine.
B) Would this produce a usable engine for the street?

Regards.
Speed eight.

Speed Eight, I'm checking that I understand your calculations... Your results are in lbf/in2?

[jcpgasoline]

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...

[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.

[jcpgasoline]

DonkeyApple said:

I'm not sure it is that much of an issue as you can walk away from the warranty liabilities overnight if it transpired that there was a catastrophic issue accross the board.

I think that enough rebuilds have been done, with enough time and miles to sufficiently justify the ballsy marketing gamble of the '5 yr warranty'. You would also assume that if this was thought out properly there would be an 'insurance premium' within the initial customer cost as well as a clause the maintains contract validity only when serviced by Power (or agreed partners) so you can amortise 5 years of servicing contract as opposed to probably losing this income stream to garages close to the customer.

It was a smart marketing move and I think it was well thought out but it would have taken balls to do this and hat's off. But there does seem to be the evidence to vindicate it.

Yes, the rebuild/warranty appears to be a structure that has been well thought through. I'd be surprised if the financial implications of the warranty hadn't been priced in. Fwiw the latest Sprint magazine has an article about one of Power's rebuilds being serviced & stripped down after 100,000 miles, which inspires some confidence.

[jcpgasoline]

DonkeyApple said:

I saw that article. I think there was another ingredient involved as well which was that it came over that the driver was prudent with how he used the car. I think some owners have been a little too brutal (as in not fully respected) in the usage of what is a high performance engine.

Yes, I think you're right. There's little downside to looking after the car, although it can be a fine line between use and abuse sometimes!

[jcpgasoline]

Speed eight said:

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.

Just found this on Wiki...

Highest specific engine output (power/unit displacement)
Petrol/Gasoline (naturally aspirated) piston engine - 118.81 kW (161.5 PS; 159.3 hp) per litre - 2009 Caparo T1 415.35 kW (565 PS; 557 hp) 3.496 L [6]
Note: 93.18 kW (126.7 PS; 125.0 hp) per litre - 2009 Ferrari 458 Italia 419.2 kW (570 PS; 562 hp) 4.499 L
Note: 92 kW (125 PS; 123 hp) per litre - 1999 JDM Honda S2000 184 kW (250 PS; 247 hp) Honda F20C engine 1.997 L

So, allegedly, the Caparo T1 makes 0.1593 hp/cc; the Ferrari 458 makes 0.1249 hp/cc; the Honda S2000 makes 0.1237 hp/cc.

A clear difference between the Speed Six and the three other engines previously mentioned is that the other three are much higher revving. In those three engines peak power is reportedly produced at 10500, 9000 & 8300rpm respectively, compared to the 4.5 Speed Six which peaks at 6700-7000rpm.

That would seem to suggest that 0.111 hp/cc isn't unrealistic for a high performance, moderately high revving engine like the Speed Six.

I think the limiting factor in all of these cases is the shape and length of the torque curve - i.e. if flattish torque can be maintained into high revs then more power will be produced per unit capacity. Before something breaks, of course!

[jcpgasoline]

Tvr Power said:

Next project once we have achieved 24 hrs endurance race

Dom

When's the 24 hr endurance race happening?

[jcpgasoline]

GT TVR said:

DJRC said:

Er Dom, so if one was present you with a boggo ish standard 4ltr Sag and request of you 500ponies and 450ft of the good stuff and enquired if your turbo plans would make that...would you say "Yes" and be flogging it as a road package?

second that, but surely it won't need a turbo for 500 bhp? There is a 4.3 with 480 bhp ...

We might be a step closer to the 500 mark, naturally aspirated. My Tuscan S has had it's 4.5 upgrade completed, so after the running in period the car will be mapped and the torque & power measured. I'm informed that the Tuscan S exhaust is less restrictive (better flow) than both the Sagaris and the standard Tuscan, which should result in more power. This could be interesting...

[jcpgasoline]

Picked up my Tuscan S with it's new 4.5 rebuild on Saturday and drove the A10 through to central London - fortunately before the riots started...

First impressions: Runs smoother, loads more low rev torque, quieter top end, more induction noise.

Didn't notice any additional heat sink into the cabin.

Oil pressure 15-20 psi at idle, high 60's at 2500-3500 rpm.

Slightly less than 1000 miles running in to go...

[jcpgasoline]

Or sooner in my case, buy without Syvecs.

[jcpgasoline]

tail slide said:

dvs_dave said:

Normally sequential injection is only better than batch at lower/intermediate engine speeds. In the case of the Speed Six though, at WOT/max. power the injectors can't physically pulse quick enough as they're being commanded to pulse every revolution rather than every other revolution as in a sequential system. Because of this high frequency they don't seat properly between pulses so end up not being able to deliver the correct fuel amount. Ever noticed how the Speed Six has a tendency to lean out at high revs/maximum power (very bad for the engine), regardless of mapping? This is why. Prolonged use at high speeds also causes the injectors to overheat.

Among the correct info you have, this part is incorrect I'm afraid; the Bosch injectors used by TVR Power DO have enough flow - and crucially good enough atomisation - even up to 7800rpm. For my 4.2 I was quite neurotic about this after previous badly set-up S6 engines, so verified it independently with a Bosch/Fuel injection specialist who checked the new injector spec and actual performance AND added a separate knock sensor to monitor it all. The only further issue was one I identified myself and have posted on here about - the heat soak into the airbox temp sensor, which is mostly eliminated by better insulation of it.

Engine's now done 17k miles, and fuelling at WOT remains in correct range, and no detonation being flagged up by the knock sensor - which I know works because it did flag it up with the initial trial map, under snap-throttle acceleration when hot, from peak torque rpm upwards. I was advised by many who should know, that the engine could be run slightly leaner (than the theoretically correct stoichometric ratio it's now at) but not at full acceleration, hence my view that there can be no more power under WOT, until proved otherwise....

Gents,

I'm curious to know under what conditions (throttle, engine load, rpm) have you encountered detonation? It seems a lot of the chat seems to be about detonation occuring at mid to high rpm with wot, but what about opening throttle at lower revs (e.g. 2000 rpm)? Any problems there?

[jcpgasoline]

So I had my car out at Bespoke Performance's driving day at North Weald Airfield on Sunday...

It was the first chance I've had to really test the car's performance with the Power 4.5 SS in it and even though I couldn't hold her at high revs because the final mapping hasn't been done yet she was just SO MUCH FASTER than everything else there, including two Tuscan S Mark 2's, a Chimaera 500 and a 4.5 AJPV8 Cerbera. She quite literally blew them all away. The car was by no means slow as a 4.0S before the rebuild but this is now just bonkers quick. It's empirical I know, but there is just so much power on tap.

Understandably I had a bunch of passengers over the course of the day all of whom were astounded at the power and acceleration. So probably a few more requests for engine builds heading Dom's way soon...

Anyhow, back to the car. The exhaust pipes have a few dents in them which are restricting flow so I'm having these replaced with ACT's big bore pipes sometime within the next couple of weeks.

After that she should soon be ready for the final rolling road mapping session as there are only a few hundred of the running in miles left to complete. Needless to say I'm very much looking forward to the results...

[jcpgasoline]

s5tvr said:

jcpgasoline said:

she was just SO MUCH FASTER than everything else there, including two Tuscan S Mark 2's, a Chimaera 500 and a 4.5 AJPV8 Cerbera. She quite literally blew them all away. The car was by no means slow as a 4.0S before the rebuild but this is now just bonkers quick. It's empirical I know, but there is just so much power on tap.

Was that driving in a straight line or round a circuit and over what distance for both ? Problem is you need to know the details of the cars your comparing your peformance and in the case of a circuit the skill of the driver and / or their appetite for pushing their car hard.

I ran my T350 at Fighting Torque (3/4 mile drag race) a few years back and in one particular encounter on the face of seriously embarassed a Cerb 4.5 - the reality probably was that the driver didn't want to really rag his car and / or it wasn't in a graet state of tune ? No doubt it would have been much closer or a different story all together had I been up against a really well sorted 4.5 Cerb with an eager driver.

Yes, I do know the drawbacks with this sort of empirical comparison, but the difference really was just so clear to see.

Fwiw, there were a couple of courses laid out, one twisty with short straights, the other with a longer straight and fewer bends. The advantage I had in acceleration was obvious. (When I could get the power down cleanly!)

[jcpgasoline]

Getsis said:

Mines with Dom now for final mapping but depends when Ryan is available. Don't forget to get a print out when yours is done. It will be good to see the comparisons with the different exhaust configs we have.

Will do!