F/I Blowing motors facts

[xsnapshot]

Originally Posted by Deep Six

......

Were you on E85? 93? 91? Just curious.

[strat61caster]

Originally Posted by Deep Six

BTW there are 4 other cars with blown motors at the same shop in Orlando as I write this so yes there is an issue.

When I hear that there's 4 blown up cars sitting at a shop that tuned them, I'm not inclined to blame the durability of the engine...

[kch]

Originally Posted by Deep Six

Mine popped recently after about two weeks of forced induction. I went with the "safest" supercharger system

Your sig says you have the HBP, though, which isn't exactly safe on pump gas. Sucks that you threw a rod, though.

[Andew727]

Originally Posted by Deep Six

It can happen to anyone which is not the same thing as saying it will happen to everyone. More track days, adding power, especially forced induction simply increases the likelihood that something will break and it will probably a rod.

Mine popped recently after about two weeks of forced induction. I went with the "safest" supercharger system, had it conservatively tuned to 20 degrees of advance and a 7K limiter, have the JR oil cooler and a full blown radiator but it still threw a rod accelerating onto a freeway which cut a trench across the top of the block.

Moral of the story is that blame is not an issue, understanding the potential risk and how modifications will change the odds is. You can not bet your motor that having a good tune and cooling provides any guarantee, they just change the odds a little more in your favor. I will be starting a new thread soon focused on the choices to be made when replacing a blown motor, Thankfully I have the resources to do what I want and I really expected to eventually have a built motor or a V8.

BTW there are 4 other cars with blown motors at the same shop in Orlando as I write this so yes there is an issue.

add me to that thread when you start it. im building my motor still. would like to share and be educated as much as possible on other failures. thanks for the info.

[Andew727]

Originally Posted by makinen

Hi,
Did he do machining similar to this?
http://www.ft86club.com/forums/showp...9&postcount=24

you have to machine aftermarket rods to work with the stock pistons?!?!?!?!?!?!

dont tell me this...

[xkalelx]

Originally Posted by Andew727

you have to machine aftermarket rods to work with the stock pistons?!?!?!?!?!?!

dont tell me this...

I was going to ask about that as well. That doesn't seem right. The only reason you would have to do that is if you have interference issues with the piston and wrist pin. No one else has ever mentioned doing that before going when going to upgraded rods and pistons so I am going to disregard that modification.

EDIT: Looks like he was having interference with that rod selection and stock pistons. For the cost and trouble, I will just be replacing with new pistons when I get to that point.

[Andew727]

Originally Posted by xkalelx

I was going to ask about that as well. That doesn't seem right. The only reason you would have to do that is if you have interference issues with the piston and wrist pin. No one else has ever mentioned doing that before going when going to upgraded rods and pistons so I am going to disregard that modification.

EDIT: Looks like he was having interference with that rod selection and stock pistons. For the cost and trouble, I will just be replacing with new pistons when I get to that point.

i ended up going with a different set of rods than the skunk H beams, but still a little alarming. ive had enough problems with this machine shop being slow and dont need another delay haha.

[blueap2]

Originally Posted by Andew727

i ended up going with a different set of rods than the skunk H beams, but still a little alarming. ive had enough problems with this machine shop being slow and dont need another delay haha.

If I'm not mistaken, all aftermarket rods will need tapering at the small end to fit the OEM piston.

Talked to the guys at Pauter and they will be doing this mod for me when I buy.

[xkalelx]

Ugh. Well, that should make it an easy decision for most people then to go ahead and upgrade to aftermarket pistons. Im not an expert by any means, but paying extra money for an extra operation that inherently weakens (you know what I'm saying, dont argue with me) the small end of the rod to retain a stock piston seams so crazy to me. Just apply the cost of modifying the rod towards better pistons and have a more bulletproof setup.

[xsnapshot]

Originally Posted by kch

Your sig says you have the HBP, though, which isn't exactly safe on pump gas. Sucks that you threw a rod, though.

I think he may have been on E85. I'd be really curious to find out for sure though.

Deep Six when the failure happened were you up high in the RPMs or lower? Who did your tune? You say tuned conservatively to 20 degrees of advance. By that do you mean that you de-tuned up the upper RPM powerband to put less stress on the motor?

That's the strategy that I'm trying....so I'm interested to know!

[blueap2]

In the general sense you are right @xkalelx.

Just buy a new aftermarket piston and go with that. However, when your power goals are not over 400whp and you already have a new oem short block it does not make sense to get a new aftermarket piston which requires separating case halves, boring, honing... etc. (Which is my case right now)

Tapering rods doesn't affect the small end much since the bottom of the small end is not compromised. The bottom of the small end gets pushed during the power (ignition) cycle. The top of the small end only sees force during the overlap (intake & exhaust) cycles.

[Matt@Cosworth]

agreed
and also the stock piston isn't half bad
the top ring groove is hard anodised for a start
given this forums appetite for high ratio with boost then I can see the appeal for 350bhp builder

[xkalelx]

^^ valid points.

[Deep Six]

Originally Posted by strat61caster

When I hear that there's 4 blown up cars sitting at a shop that tuned them, I'm not inclined to blame the durability of the engine...

Multiple tuners and all four besides mine were turbo kits installed elsewhere.


This shop is just very experienced with building Subaru motors and the owners are very good friends of mine.