4.6 swap

[mjjrV8S]

Anyone upgraded their 4.0 to a 4.6? I’m going to get top hats and thinking i might us well go for a full RPI 4.6 swap……to much for the little S?

[v8s4me]

There was an 'S' with a 4.6 being advertised on Facebook earlier in the week. Of course FB being what it is. it's now impossible to find the post.

[spitfire4v8]

The little S will cope just fine. Plenty have run high power S series over the years. Indeed,the factory did a couple of 4.3s and a 5litre themselves.
I had a 355hp 5litre in my S. Greenv8s runs a supercharged 4.6. There's a 5litre doing the sprints and hill climbs.
Have fun!

[mjjrV8S]

The engine in mine is a fairly standard PTP 3.9, so i want to not only upgrade to top hat, but also gems, highlift cam, etc. any ideas of reasonably priced engine builders? RPI favourite so far but they recommend non gems, je devps - a bit pricey and V8D not tried yet.

[GreenV8S]

My V8S has a supercharged 4.6.

I have spent more on the transmission, suspension and brakes than on the engine - don't expect to just drop in much more power and have a well balanced reliable car.

[QBee]

You need advice on what cam to install, to suit the way you want it to drive and the spec of the internals.
I had mine rebuilt and the MC1 cam suited my needs best.
It makes 275 bhp with plenty of torque in the mid-range.

[spitfire4v8]

mjjrV8S said:

The engine in mine is a fairly standard PTP 3.9, so i want to not only upgrade to top hat, but also gems, highlift cam, etc. any ideas of reasonably priced engine builders? RPI favourite so far but they recommend non gems, je devps - a bit pricey and V8D not tried yet.

I'm becoming a bit disillusioned with engine builder timescales and have elected to bring any rebuilds in house now to avoid embarassing lengthy time delays for customers, so can't really offer any advice on engine builders now.

[Belle427]

I'd avoid Rpi personally,V8D are good guys but do check timescales.

[v8s4me]

How about Powers Performance?

I was happy with the rebuild I had done but that was some years ago now.

Here's the FB Marketplace add for the S1 with the V8 conversion.

https://www.facebook.com/marketplace/item/69826264...

Edited by v8s4me on Wednesday 22 February 16:17

[mjjrV8S]

GreenV8S said:

My V8S has a supercharged 4.6.

I have spent more on the transmission, suspension and brakes than on the engine - don't expect to just drop in much more power and have a well balanced reliable car.

Long term project, its already been off the road for 4 years. Whats brakes did you put on yours?

[GreenV8S]

mjjrV8S said:

Long term project, its already been off the road for 4 years. Whats brakes did you put on yours?

It's been through half a dozen upgrades over the years as power increases have revealed new weak points. Same for the transmission and suspension.

[Kooda]

v8s4me said:

There was an 'S' with a 4.6 being advertised on Facebook earlier in the week. Of course FB being what it is. it's now impossible to find the post.

I've been and had a look at this car. I presumed it had a LT77 but its the original box/diff, which duly raised my concern that is addressed later in the thread, can the drive train handle it and, the answer seems to be "NO!".

My question is, what was the original 'box diff configuration that was used in an S1 & the respective ratios?

I'm guessing that the ratios will be a bit short for that amount of torque too.

[greymrj]

You CAN search on our FB page. Use the 'Q' top right and type TVR S FOR SALE and it will bring them up.

Upgrading a V8S by upgrading the engine detail spec is one thing, and it has been done quite a few times.

Changing a V6 to V8 is quite another. We have seen a coupe of cars in which this has been done to differing degrees of engineering quality (!). The chassis are NOT quite the same and there is a great deal more to it than just dropping an odd Rover V8 engine in. Gearbox, diff, brakes, cooling, electrics etc all need to be considered.

I think I know which car is being referred to above. But at least one 'V8' that came up was very dodgy indeed and didn't even match its DVLA records. Buyer be very very aware if it is a conversion.

Another issue is resale. We now have plenty of evidence that converted or customised cars do not normally sell as well as well presented more original cars.

[GreenV8S]

One of the biggest factors IME that determine drivetrain longevity is how successful you are at avoiding wheel hop and wheel spin-up. As long as the wheel is only carrying the vehicle weight the drive train is largely OK with loads limited by the available grip. The main problem is the diff wearing out because it spends so much time around the limit of grip.

But the extra power combined with trailing arms and a not particularly stiff chassis means it's easy to provoke wheel hop. It's also very easy to spin up a wheel when you break traction. Both of these produce snatch loads much higher than normal which will destroy transmissions. Suspension setup and driver behaviour play a big role in that. The original LT77 was OK for sub 200 ftlb. Mine has been uprated a bit but still essentially an LT77 and is surviving roughly double that with (touch wood) no problems so far, but that's because I treat it carefully.

Similarly for the brakes - the more power you have, the more potential there is for poor driver technique to dump heat into the brakes.

[Kooda]

greymrj said:

I think I know which car is being referred to above. But at least one 'V8' that came up was very dodgy indeed and didn't even match its DVLA records. Buyer be very very aware if it is a conversion.

Hmmmm, so much to unpack there……..

All in all, I don’t think it’s quite the right thing for me, right now.

Thanks for your thoughts.