The V8 Owners Forum -

cars less than 1000KG, either a 3.5 or 3.9, if i put in a mild/ast road cam what kinda revs will the engien freely rev to?

im hopeing to rev up to 6.5 - 7 maybe? or is this asking alot?

i dont want to lose driveability but dont mind losing few mid range foot pounds as it has more then enough as it is!

anyone recomond anything? an how far they freely rev to?



Ralph

The valve gear isn't any good for those kind of speeds, the hydraulic lifters pump up. You'll be doing well to get over 6K.

Red line on a Range Rover is 5500 I think.

Chris.

As Chris says, it not really a case of simply replacing the cam with something more meaty.

For 6.5-7k revs the valve train would need beefing up with either steel parts (rockers/pedestals/shafts) or at best a set of roller rockers (which you're looking at about £420 from V8 Tuner alone).

However, there are people who use standard stuff without issue, there does seem to be an element of lady luck (well, there is with anything I guess!).

You can get cam kits, which will provide not only the cam, but new lifters etc. for a resonable amount of money (think around £400 for the good kits)

Upgraded pushrods might be a good idea. And if you're revving it over 5.5k ARP bolts are a MUST; Mains/Rods/Heads - that's another £300 right there.

But as you're tuning the engine, you're getting into the realms of easily destroying the PG1 gearbox you want to use . . . IMO you're pushing it with a standard RV8 never mind a tuned one!

I run to 7k on a regular basis, nothing to fancy apart from a silly mechanical cam, and a set of ARP rod bolts

Change the gearbox / diff to get longer legs.

I did suggest a diesel one on another thread

Ian

maybe 7 was over the top, my main reason for askign was cause i want more higher up power as its a light car and not a range rover.

i have just been offerd a 3.5 EFI 89/90 (probly hot wire?) engine with free good MOTed ranger rover se... air con/leccy seats/lether seats ect etc £350


i think its 165bhp @ 4750rpm with 206 LB ft @ 3200.


on the other hand the SD1 vitesse was 190BHP @ 5280 and 220 LB Ft @ 4000

its easyer to start with a range rover cause

A i already been offerd one,
B they are EFI,
Ci know loads a landrover people!

so can i get the Range rover engine to kick out similar or better figures to the SD1 vitty?

also does the range rover have a rev limiter? as this could decide for me!


i already have a very long legged box from a rover 220turbo, 3.6 final drive which is highest there is in my box.



Ralph


edit: guessingthe engien will rev bit more than its max output, since my previous engine produced its max power at 6k but in a race its fastest to rev it to its 6.8k limit, so if the V8 would rev to 5.5k?

then it would do these speeds in each gear....

29.2 50.3 70.9 89.7 121.2

main thing i wanna d is free the engine up a bit so it drives like a car and not a range rover.

Thing is (and there's lots of reasons why), v8's are generally not like a 4 cylinder engine. Although there are some modern exceptions, a large capacity v8 is generally a low revving torquey motor, and that coupled with the noise makes for a great drive.
You don't need to keep changing gear when you want to overtake, you just nail it and it pulls like a train. Completely the opposite of the VTEC type stuff where a good stir of the cogs before attempting anything is de-rigeur.

But going to your point, I believe the differences between the vitesse and the Range Rover engine (performance related wise) are:
Compression - RR=9.35:1, Vitesse 9.75:1. Pistons set compression
Valves - RR=standard, Vitesse=waisted behind the valve-head
Camshaft
ECU.
Distributor curve
I don't think there are any other performance related changes.

So you could get all those bits and swap them over, and presto, lots more power. Or just get a different camshaft and lifters.

Chris.

Oh yes, and none of the 3.5 or 3.9 engines had a rev limiter. The engine limited itself mechanically at around 6K.

Another point about a high revving engine is that the friction in the crankshaft big engs puts a huge sideways load on the pistons, especially when the engine is cold (as 20/50 is a thick oil). This can break con-rods. So don't try for 6K+ on a cold engine!! It's a well known problem.

Chris.

sorry yes i probly am compainring V8's to my previous engines! i have never owned an engine bigger than 2.0L lol. tho use dto reguly borrow bros V8 landy when mine broke! i do have variable valve control now but its the modern high tech stuff i kinda wanna get away from.

its all very well but having loads a horses coming from a high tech motor dont last long an in rovers case has reliability issues.

anyway, cheers for info about whats different, i can get heads skimed, and would like to change cams anyway, is it easy to get after market ones which would be similar to vitty ones?

well hopefully break the RR then an have a V8!


Ralph

Dont see any point in running a RV8 to them rpm's.
My old 3500 went to 7400 on the dyno, but the real torque was at 4700 rpm.
After that it started to drop off.
With a 50 shot of gas she made 257 at the fly on the original low comp (8:1 with comp gaskets) V8. I ran a 150 shot after that but didnt put it on the rollers.
I now run a 4.6 with a higher CR and she has fantastic power under 5000 rpm. But when I hit 5500 rpm she stops pulling as well.

ok then engine like the vitty, max output at just over 5k, would it actually rev ok to 6? like if you where flat out in top?



Ralph

mgbv8 wrote:Dont see any point in running a RV8 to them rpm's.
My old 3500 went to 7400 on the dyno, but the real torque was at 4700 rpm.
After that it started to drop off.
With a 50 shot of gas she made 257 at the fly on the original low comp (8:1 with comp gaskets) V8. I ran a 150 shot after that but didnt put it on the rollers.
I now run a 4.6 with a higher CR and she has fantastic power under 5000 rpm. But when I hit 5500 rpm she stops pulling as well.

I agree totally with you Perry, 7k is pointless for racing, but it is nice to have I have my shift light set 300rpm before the torque starts to decay, so I should keep the accellertion going, BUT, I also intend to see what the car tops out at, With the 7k limit the car should pull somewhere above 160mph, dont know if the 2mile straight is long enough at Brunters, but with a bit of sniff that should help to get it up there, Take the bottom corner at 70+ then hit the button for a few seconds

Ralphh85 wrote:ok then engine like the vitty, max output at just over 5k, would it actually rev ok to 6? like if you where flat out in top?



Ralph

Completely depends on gearing/aerodynamics, if its geared to 100mph then yes 200 no get what I mean?

I'm hoping to ge the new setup on the dyno soon. I'm curious to see where the new 4.6 + different cam setup makes best torque.

Ian
On normal road tyres 24.5" (not the 22" BFG's) and with the old 4 speed + O/D box fitted I did a paced run against an ex police T5 and I bottled it at 147mph. Your tina should make 160 I reckon. I was on the blower to my mate in the T5 who was pacing me and he said he was clocking 147. My speedo was jumping about a bit though. She was certainly running out of puff by that time. And the wind noise was deafening.
I'm not sure if she would have done 147 on her own as I was behind the T5 in his slip stream. But it was a good hoot anyway.
I also set my shift light to the top of the torque range for my engine. It then drops back about 700 rpm and gets me back at the start of the torque band.
When I broke an axle back in 2006 at the Pod she revved to over 8000rpm. But it didnt break. I only put that down to a good balance though.

I've see those type of speeds in ths GT40 it was still pulling but I bottled out (Need to get onto a really long runway some time and try again)
But it is low and wide so may be more stable than most with less front area.
But it sure does seem to tramline and get skittish at those speeds.
That is about 5000 in 5th with 26 inch diameter tyres on the long 5th and long diff on the UN1 transmission.

Ian