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Hi

I have a very loud rattle in the higher rpm range it starts at 3900 rpm and up coming from the engine bay, i'm not sure if it's tune related or mechanical i have included a xdl which shows alot of retard and some knock thanks in advance.

could be anything including detonation. Without physically looking at the engine, we'd only be guessing.

Perhaps post up a video on youtube?

Thanks mate.

I ruled out the tune by putting the memcal into another vs l67 and had no rattle. Thanks

Quick test is to remove blower belt. That can eliminate supercharger noise, especially the coupler as these flog out and can rattle / clunk.

L67PSI wrote:Quick test is to remove blower belt. That can eliminate supercharger noise, especially the coupler as these flog out and can rattle / clunk.

The rattle goes away with the blower belt removed, charger has new coupler, so I thought maybe the rotor pack so I swapped the charger over with another which had a new coupler also and it still rattled, have also replaced the tensioner to eliminate that.

Thanks

Take a look at the harmonic balancer, it could be on its last legs and starting to come apart internally hence it could explain the noise when there is a load from the blower

Think vlads on the money.

vlad01 wrote:Take a look at the harmonic balancer, it could be on its last legs and starting to come apart internally hence it could explain the noise when there is a load from the blower

Charlescrown wrote:Think vlads on the money.

When I replaced the timing chain I went over the balancer really good to check for any sign's of damage, could not even find a split or perishing in the rubber and I tapped with a rubber mallet for any rattles nothing. Thank you both for your idea's I know it's hard to diagnose without hear it.

Balance shaft bearing going maybe

delcowizzid wrote:Balance shaft bearing going maybe

Sorry mate I should have posted that I replaced the timing chain with a double row and deleted the balance shaft.

Mods.
86mm pulley reads 6 psi in lim, mace 1:98 rockers, pacemaker extractors, 2 1/2 catback, ported charger (rattled before porting).

Thing's replaced, catalytic converter, o2 sensor's, timing chain, belt tensoiner's, water pump, plug's, lead's, coil's, dfi, fuel pump genuine walbro 342 not eBay, fuel filter, 82 degree thermostat, transmission and converter.

Thing's borrowed too try, maf, fuel rail and injector's from a perfect running car, standard size supercharger pulley.

Sorry for not posting this before thanks.