Building a new shortblock and looking for some opinions on rods

[Steve]

I have built a few mid 10 second 109's and the in the past I have used stock rods with Speed Pro pistons and never had a problem. I am building a new 109 now and I am planning to push this motor into the low 10's and maybe even a 9.99 pass just so I can call it a 9 second car! I know the stock rods have proven to be very reliable but it wont cost me much more to upgrade so I am trying to decide if its worth it. I have a forged 3.4 crank I am going to use and I am either going to go with a new set of 2 dot rods for $129 or I can get a set of Scat forged h beams for $375(I would like to support one of our vendors but all of the vendors want $550 or more for a set of forged rods). I will have to go with a Probe forged piston to work with the Scat rods but that will only be an additional $40 over the Speed Pro piston. So my question is it worth it to spend additional $300 to go with the forged rods or should I stay with the new 2 dots and go with whats proven to work? I don't mind spending the $300 if its worth while but I do not want to waste it if its not needed. Thanks

 

[bison]

The off the shelf probe pistons won't yield much CR.

 

[750H.P.V6]

If you're running a forged crank and planning on pushing the car into the 9's I'd say a decent forged rod is money well spent. BTW, J&E have forged pistons off the shefl too.

Neal

 

[Steve]

Thanks for the replies!

Bison, the off the shelf Probe pistons yield a lower compression than normal turbo Buick pistons? I did not know that, I figured there were comparable to other turbo pistons. I know the JE pistons are great pistons but they would add another $300 making the rod upgrade $600 over new stock two dots and Speed Pro pistons. Again I am not opposed to spending a little extra for piece of mind I just want to make sure I am using my money as wisely as possible.

 

[750H.P.V6]

I'd spend the money now if I was in your shoes. Most people end up upgrading their combo's down the road so it's always nice to over build things in the first place to give you an adequate safety margin later. I have also seen a number of stock rods bend and at least 1 break in high H.P. applications.

Neal

 

[Scott Atk]

I had great luck with the Wiseco pistons. They don't have a full perimeter skirt like the J&E's but they worked for me and are much cheaper.

 

[kidglok]

will you be running a forged crank?

 

[bison]

Thanks for the replies!

Bison, the off the shelf Probe pistons yield a lower compression than normal turbo Buick pistons? I did not know that, I figured there were comparable to other turbo pistons. I know the JE pistons are great pistons but they would add another $300 making the rod upgrade $600 over new stock two dots and Speed Pro pistons. Again I am not opposed to spending a little extra for piece of mind I just want to make sure I am using my money as wisely as possible.

The piston specs are listed with them. You can easily calculate the CR with the info given. If you are looking for one 9 sec pass and will spend most of the time running slower id run a set of stock rods but id be ok with it but id use the best fuel i could get. Once you go below 10.50 the cost to gain reliably increases dramatically. You will need to be able to make 100hp more with the same parts. If youre worried about spending $1200 on rods and pistons id pick a more reasonable goal of high tens. below 10.50 you cant have one thing go wrong under power or you will be spending a lot more $.

 

[Steve]

will you be running a forged crank?

I will be running a 3.4 stroke Eagle forged crank.

 

[Steve]

The piston specs are listed with them. You can easily calculate the CR with the info given. If you are looking for one 9 sec pass and will spend most of the time running slower id run a set of stock rods but id be ok with it but id use the best fuel i could get. Once you go below 10.50 the cost to gain reliably increases dramatically. You will need to be able to make 100hp more with the same parts. If youre worried about spending $1200 on rods and pistons id pick a more reasonable goal of high tens. below 10.50 you cant have one thing go wrong under power or you will be spending a lot more $.

I am not opposed to spending the extra but I do not want to waste the money if its not needed. My old car went 10.46 with the stock crank(cut 20/20), rods and pistons and two center billet mains and I think it could have gone faster but I was really pushing the boost because the car had stock TB, stock unported intake and mildly home ported irons with stock valves. I think I am going to go with new stock rods and Speedpro pistons. I will have about $2k in the shortblock including the girdle so I hate to spend an extra 60% to upgrade the rods when the stock rods have proven to be pretty reliable. I am planning to run E85 and alky. I already have a new Alky Control kit that I plan to use and here in the midwest E85 is everywhere and cheaper than 93 by a good bit so I figured I might as well use that also so hopefully detonation wont be an issue as long as there is no failures invloved. I will apply the $1200 that would be needed for the rod upgrade to freshen up another 109 motor I have and have a spare in case things don't go well!

 

[bison]

I am not opposed to spending the extra but I do not want to waste the money if its not needed. My old car went 10.46 with the stock crank(cut 20/20), rods and pistons and two center billet mains and I think it could have gone faster but I was really pushing the boost because the car had stock TB, stock unported intake and mildly home ported irons with stock valves. I think I am going to go with new stock rods and Speedpro pistons. I will have about $2k in the shortblock including the girdle so I hate to spend an extra 60% to upgrade the rods when the stock rods have proven to be pretty reliable. I am planning to run E85 and alky. I already have a new Alky Control kit that I plan to use and here in the midwest E85 is everywhere and cheaper than 93 by a good bit so I figured I might as well use that also so hopefully detonation wont be an issue as long as there is no failures invloved. I will apply the $1200 that would be needed for the rod upgrade to freshen up another 109 motor I have and have a spare in case things don't go well!

If it were me id skip injecting alky if e85 was readily available. The E85 alone will be more than enough to meet the hp goal reliably. The alky at that level will add in a tuning variable that is not needed.