The V8 Owners Forum -

Just get some dynoresults my home buildet 5.2l Rover.

recon 5.2litre
V8 developments M238 Cam.
10.7:1Cr
Siamesed plenum.
45mm trumpets
41,5mm primaries. 3" main pipe
stage 4 valves (home ported heads)
3.5bar fuel pressure
Haltech engine magnament
MSD dizzy + 6al box
JE steel billet flywheel 7,8kg + sachs bmw clutch. LT77 box

Results at wheels

1 run 294.44hp@5470rpm 8static advance + 28max advance.

Best run after adjustment, 301hp@5460rpm 10static advance + approx 30max advance.
Fuel curve is 100% correct @5500rpm when i go to dyno. so my adjustment are perfect on the road. Leaning + slightly richer will drop power immediately.

last year torgue curve is 520Nm(382.35lbft)@ 3200rpm and ignition max advance is reachet approx 3500rpm. this year max advance is reachet approx 3000rpm, so torque also drop slightly. So need to fit stronger springs to increase torque back to correct level. Also when we adjust ignition timing, low end torque drops.. Now result are 504Nm(370.58lbft)@3400rpm.

So 17hp more than last year when it run lean..

Estimated flywheel power 335hp. 35hp loss at transmission..

Excample 48hp loss power..
http://www.v8forum.co.uk/forum/viewtopic.php?
t=5509&postdays=0&postorder=asc&start=150

So how to calculate correct flywheel power?

So quite happy for my results.. Nex winter i fit jenvey 48mm throttlle bodies, hope to get 20hp more?

I have seen on pistonheads rover v8 dynoresults, but i can´t found that link anymore. Anyone?

I want to see others dynoresults..

Interesting stuff!

I hope that you have a spare LT77 gearbox handy!

Do you need that big TBs, 45TBs will support 400hp and possibly a lot more, the reason I say this is the TBs dont have restrictions like venturis to hinder airflow

Just receive new Tremec T5 (m-7003-z) box. LT77 is spare then.
I dont have anythink proplem with the LT drived over 5000km, and still going to SD1..

Spoke to Jenvey, John Eales, V8 developments and our local Jenvey dealer, they all recommend 48mm bodies.. 45mm is minium of that size of engine.. and if i someday order wild cats or TA-performance heads, i can fit those then..

Mmmmm, that means Im in trouble , I run 42s on my 3.9 without any problem, you seem to max out at 5.5k, so you probably run it to 6k, I cant see a engine running 1100cc needing around that much more air, I think about 30%+more airflow
Not that I am doubting what you have been told, but I would be thinking 45s on a 302 size engine just to keep throttle response, Im still going to run my 42s on my new 4.6, I just hope they wont hold it back

I have no idea how to calculate air flow but if you take a single 72mm throttle body it has a sq area of 4072mm sq

8 * 45's would be 12725mm sq, 48's 14478 mm sq and 42's 11084 mm sq

Anyone advise on how to calculate flow based on area

Well John Eales say that you need +50mm throttle bodies + cross over manifold if you need over/near 400+ for rover 5.2litre..
You can get pretty dam close to 400 for 48mm ITB setup.. approx +380hp?

50mm sounds big to mee.. But hope he knows?

Also Jenvey say that 45mm for 350bhp applications/+5.0l engine is minium.
Also our local Jenvey dealer/engine guru n(over 30years building engine and he has made/plan his own engine magnament system called HESTEC) say that 45mm at least..

V8 Developments, not sure if it Shaun, he recon 48mm if you want to broke 350hp limit..

Also BMW e34 M5 use 45mm throttle bodies 315hp and still runnability.

Theoritically your 42mm setup sounds small for 4,6?

r2d2hp wrote:I have no idea how to calculate air flow but if you take a single 72mm throttle body it has a sq area of 4072mm sq

8 * 45's would be 12725mm sq, 48's 14478 mm sq and 42's 11084 mm sq

Anyone advise on how to calculate flow based on area

Not sure, but i understand that all cylinders will see 72mm throttles?
Its not only size of the throttle.. TB has got individual runner´s so other cylinder back pressure dosen´t bother anymore vs plenum.. Thats why it will produce more power? I think this is the biggest reason?

I have just got off the phone from a mate who builds serious cylinder heads, takes a long time to do them but they generally superb, he is thinking along the same lines as me, 42s are right on the limit of a 4,6 and will probably hurt top end power but will make for a good torquy engine,
Tomorrow I will measure the bore of the TBs just to confirm the size

Managed to get up the garage and measured my TBs------they are 45s, Im sure they were meant to be 42s