Extractors?

[xstriple]

Hi Gang,
Can anyone recommend a set of exhaust extractors or even if I will get much benefit from a 3.5 in a '91 from doing this please? The engine is getting a full top-end reco and ditching the clutchfan for a thermo system.
Cheers

[blitz]

I put Geine on mine - sounds sweet not sure how much difference it made as it was done during a major rebuild so heaps of other stuff done at the same time

[SuperchargedSport]

I've got Janspeed extractors on a 4.6 in a RRC, i cant say they do much.

I wouldnt take them back off, but if i was doing it again id just put sports mufflers in it and be happy with a rumble. Especially on a 3.5 they wont do anything. Its very difficult to get power out of the rover v8s. I mean you can get more, but not enough for the money it takes. I guess thats why so many people rip it out and put a holden 5lt in.

I have had trouble recently with the twin thermo fan setup i have on it, and i took them off while i wait for a new thermo controller and put the viscous fan back on, and its definetely slower on take off. mid range is about the same. But its slower on over taking at full throttle.

I'm looking forward to putting the thermos back on....

[101RRS]

The general consensus is that extractors do little for a Rover V8 as the standard manifolds already work similar to extractors.

Garry

[400HPONGAS]

Actually its because all Rover V8's are severely "Port Choked" If you cant get anything in ,why worry about trying to get it out !!!Its as silly as fitting one of Them Later "Thor" manifolds ,total WOFTAM

[brenno]

Its as silly as fitting one of Them Later "Thor" manifolds ,total WOFTAM

I'd heard (on this forum too) that there is significant and noticeable increase in torque. Do you know differently, or have a different experience??

[400HPONGAS]

It slightly changes the torque curve , no more than original 3.9 does ,common with all tuned length runner types . You gain better by putting in the cam at 4 degrees advanced !! redo the fuel and ignition maps while your at it
1995 disco 190hp/142kw and 236lbft/320nm
2003 Disco 188hp/140kw and 250lbft/340nm @ 4750

[PhilipA]

IMHO, having fitted one, it is well worth the considerable effort.

The aim of a Thor is not outright power but to lower the torque curve. the runners on a Thor are over a metre long compared to about 25CM for a 3.9 manifold, and have a taper to give a Hemholz boost at low revs.

I have posted dyno charts many times showing a total 50% increase in "tractive effort" from about 1200 tapering to 3000 , with a 10% loss over 4000. This also includes piggyback Unichip controlling timing and fuel. This greatly improves the highway and towing performance and the car feels much more lively .

The port limitations really do not influence the fitting of the Thor as you are not looking at high revs. In any case I disagree that the inlet ports are poor on a RV8. It is the exhaust ports that are the problem, exacerbated by a very poor casting in some later engines like 3.9s.

On heads I modified I gained 7% by opening the inlet ports and removing the guide completely from the inlet port. However I had to spend many hours on raising and cleaning the exhaust ports as there was a large step where the casting met in the middle of the port immediately below the valve.
Regards Philip A
Attachment 46046

[400HPONGAS]

How can you draw those conclusion from that HAND DRAWN DD printout ! No torque curve/tractive effort plot at all. No mention of which gear you in ,(back calc RPMs)what the ramp rate was and no comparison between just the manifolds ,(without Unichip and headwork)
What ? disagree that the inlet ports are poor on a RV8., well take any heads to a pressional head porter and the will laugh themselves silly !!!You ever heard of Volumetric efficicentcy ? I build engines at around 107% VE ,Those heads choke it down to 85%.The port Choke comes from The Pushrod chokes , or for those that dont understand ,its the CSA your limited to because the Pushrod holes are so close to the runners.As for that Disastrous Short turn Dump ,you must be joking !!
Unless you fit Buick 300 or Wildcat heads ,youn never make anything decent out of any Rover V8
Your graph ,shows the diffence between what and what , Unichip and no unichip perhaps ?
Why on earth show a Graph on Horsepower/KW to demonstrate some Percieved change in Torque ?
Try plotting that all again using Torque x (RPM /5252)=HP and you will see the old Hemholz theory is useless for Variable speed engines,the useable torque range becomes way to Narrow .

[101RRS]

I think you should stop stirring up people who like the Rover V8 and finish putting that radio in your D3 so I can also do it.

Garry