Rod knock

TTA855

White lightning drinker
#1
My tta is down on power at, and approaching, wot; it won't make full boost. My mechanic tells me he hears rod knock, and the ecm is misconstruing the noise as pre-ignition and pulling timing. He tells me the engine must be pulled and rebuilt, with new, one size bigger pistons, and a new crank unless it can be turned. Does this sound right?

If so, should I go ahead and bore it out to the maximum to increase displacement and power? What is the maximum bore size? I remember ATR used to offer a 4.1 liter engine; is this the max?

Also, I would appreciate advice on which pistons, crank etc. to buy. I assume forged pistons, but is there a particular brand that is best for our ttas?

Thank you!
 
#2
Oh man.
I would double check that diagnosis with another experienced mechanic to be sure before tearing down the motor.

If confirmed rod knock, be sure to find a machinist/engine builder who you trust and knows the turbo buick engine block very well.

Good luck!
 
#3
Do you have a Scanmaster? That will tell you a lot of what you need to know, if the springs are weak that will make it nose over as well.
As far as the rebuild goes a stock eng. will hold together fine for street use, as long as you stay on top of the tune and i would never bore a eng. more than needed unless it is all out race and even then its not necessary.
I would start with a scanmaster and powerlogger, learn how to use it or you will be doing all of this over again, if it even needs it in the first place, for a forged short block you can plan on spending 6-10k which by the way will not make it any faster by itself.
 

TTA855

White lightning drinker
#4
Do you have a Scanmaster? That will tell you a lot of what you need to know.
I would start with a scanmaster and powerlogger.
Thanks Robert. I don't know anything about the Scanmaster, so can you explain how it would help me diagnose my knocking noise? (BTW, it doesn't knock when it is cold, only after it warms up). Thanks!
 

TTA855

White lightning drinker
#6
The mechanic that diagnosed it as rod knock is Denis Koch with Tune Tech on Monroe in Spokane. The engine builder I will use if necessary is Cassell Engines in Spokane.

Do you have any advice on where I should buy the parts? GN1 Performance? Also, is it worth the extra cost to buy a roller cam? Thanks!
 
#7
Is that mechanic familiar with v6 Turbo Buick engines? Familiar as in they have built more than one? Be very careful with who you choose, these are not SB chevys and yes you want the roller cam, they are cheaper than another rebuild... Flat tappet cams are paperweights.
 

TTA855

White lightning drinker
#8
yes you want the roller cam, they are cheaper than another rebuild... Flat tappet cams are paperweights.
Thanks Robert. My engine has been pulled and sent to the builder; he is in the process of tearing it down. He quoted me $750 for a roller cam, and told me there is none with the exact same profile; his will be a little taller but not too aggressive. Do you know a source for a roller cam with the factory profile? Or do you recommend I install a little more aggressive cam?
 

TTA855

White lightning drinker
#10
Thanks for all your advice Robert. The preliminary report from the engine builder is the knock was caused by piston slap in cylinder #1. He also found a crack in the head between the valves and is sending it to Seattle to be fixed. The crank main bearings show significant wear. He recommends I start using racing oil with zinc. He is installing a roller cam from Comp Cams, their 258HR with 206/206 overlap at .050 inch lift.

I bought a Scanmaster and Boostane octane boost, and will be carefully monitoring the knock retard in the future.
 
#11
Thanks for all your advice Robert. The preliminary report from the engine builder is the knock was caused by piston slap in cylinder #1. He also found a crack in the head between the valves and is sending it to Seattle to be fixed. The crank main bearings show significant wear. He recommends I start using racing oil with zinc. He is installing a roller cam from Comp Cams, their 258HR with 206/206 overlap at .050 inch lift.

I bought a Scanmaster and Boostane octane boost, and will be carefully monitoring the knock retard in the future.
Did you get the scan master g? That’s the one you want. Data logging Bluetooth. The problem is once you see the knock the damage is done. Do you have e85 near you? If so time to switch over. Pretty much takes care of knock issue


Sent from my iPhone using Tapatalk
 

TTA855

White lightning drinker
#13
Mods prior to the engine rebuild:
Test pipe and stainless 3" cat-back with straight through muffler
160 tstat
K&N 9" filter in lieu of stock air box
Screens removed from MAF
Garrett Stage 3A turbo with adjustable wastegate running 19 psi
255 lph fuel pump, 47 lb injectors, Bosch adjustable fuel regulator
Tuned stock chip to advance timing (29 degrees base and 56 degrees peak) and drop A/F to 11.5
Driver side valve cover vent
EGR disconnected
Stage 1 shift kit
Dyno'd 310 hp and 420 lb/ft at wheels with octane boost
 
#16
It may be written on the chip but it doesn't matter as the only thing i would use it for is target practice, if you are going higher than stock boost you need Alky or e85, both have pro's and con's but my personal preference is alky, no matter which you use you have to monitor whats going on and the easiest way is with a scanmaster and powerlogger, that along with a turbotweet chip and electric fuel pressure gauge will help keep it together, there is a learning curve to these eng's ( compared to others ) but it's not bad when you get the hang of it, in fact if you're not careful you may even have fun doing it...:)
 
Top Bottom