D90 4.6 V8 - weak..

hi guys,

bought D90 1996 4.6 V8 engine type 46D
holley carb, LT77 (reverse gear close to 1st)

but from such engine expecting more power - actualy its weak..
theres no problems with starts
idling isnt so perfect - seems too low revs, or maybe carb isnt so smooth as injectior.
when reving sounds seems ok

my question.. can small silencer cause weak engine power ?
theres mounted 2 small silencers, 1st looks like home made (welding on it) not sure if something inside,
second seems normal. but both are small.
also when driving - car is too loud, when pressing gas pedal it sounds like rocket but accelerating as 300tdi :-(

really not sure if silencer can make such difference in power ?
maybe to replace 1st silencer with NTC4615 ?
or maybe theres some other prob..

attaching pics - both silencers, and carb

1st silencer (home made?)


2nd


holley

I'd start with getting the carb set up properly and check timing

missed to tell,
theres MSD 6AL mounted..

Needs the correct coil. Think they recommend the blaster.

Nice job! In an ideal world therevwould be no silencer just straight pioe. As long as the box youve madevcan handle the flow your all good. If in doubt unbolt the silencers completely somewhere away from the neighbours and try the car. Not for too long mind we don't want overheating especially on that v8 if you get a suden power increase you found the issue.

You know I've never understood how Rover could make a 4.6 litre v8 that only makes 220bhp and 280 lb ft of torque! When jaguar were making at the same time 4.0l v8 that mere turning out 290bhp at 320lb ft of torque and at a lower rpm!! The jag unit uses less fuel under a similar load, is considerably smoother and infinitely more reliable.

It's no wonder Rover struggled lol.

Yeah - the 4.0 v8 jag engine is a cracker - both for power and economy - my dad has a 1998 xj8, and it's a very nice drive indeed, makes the v8 in my 50th feel decidedly old & asthmatic.

The supercharged jag v8's are something very special indeed....

captainbeaky said:

The supercharged jag v8's are something very special indeed....

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Just more modern than a 1950s 2 valve per cylinder single cam pushrod v8

fizzyhair said:

You know I've never understood how Rover could make a 4.6 litre v8 that only makes 220bhp and 280 lb ft of torque! When jaguar were making at the same time 4.0l v8 that mere turning out 290bhp at 320lb ft of torque and at a lower rpm!! The jag unit uses less fuel under a similar load, is considerably smoother and infinitely more reliable.

It's no wonder Rover struggled lol.

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I suppose what I don't understand is, how people can be so blinkered.

The Rover V8, or aka Buick 215 small block as it was originally. Is an OHV engine of the 1960's, using mostly 1950's design.

The AJV8 on the other hand is a DOHC unit designed in the mid 1990's, so has 30-40 years of advancement in it's design.

Lets not forget you are also using the car based version of the engine as a reference, while most 4x4 engines are de-tuned from their car counter parts. And indeed, when Land Rover started the AJV8 they used the 295hp 4.4 litre version. Which while an impressive engine, doesn't carry the same specific output as the early 4.0 litre.

bradsystem said:

hi guys,

bought D90 1996 4.6 V8 engine type 46D
holley carb, LT77 (reverse gear close to 1st)

but from such engine expecting more power - actualy its weak..

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How weak is weak? Do you have a comparison?

For example, a stock 4.6 auto p38a should easily smoke a modded good running Tdi Defender.

So a 4.6 in a 90 should fly.

I'd start with a look at the carb and general running. If it isn't running right, then tracking down additional other power losses will be a challenge.

how weak it was ? similar to 300tdi..
but few weeks later..
got new spark plugs, wirings, coil,..
was surprised when spark plugs was removed, previous owner used 3 different spark plug types..
wiring at spark plug side was ok - even i checked this before. but was very surprised at distributor side (not checked before)
there was huge oxidation, even broke cables when removing them from distributor..
after wire replacement engine runs ok for few kms. but on iddling not smoth again..
today distributor cap was removed, another green oxidation.. cleaned and now it seems ok, will make some other tests soon..
also realized theres no silencers at exhaust but resonators.. replaced one with proper silencer and now its better.. not so big noise inside/outside car

question - is there some web shop in uk or eu which have distributor wrenches for 15mm screw ?

Use a ratchet spanner

If your plug leads are in that state wot state are your filters,oil,coolant etc in?

Iann said:

If your plug leads are in that state wot state are your filters,oil,coolant etc in?

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Yes, good service might help with his power issues as well. Filthy blocked up air filter will reduce power quite a bit on its own.