Building a 9.5:1 Non-Stroker... What cam...?

[jasjamz]

Here is what I have now...
109, .020 over, 3 steel mains
Steel crank, rods and Diamond pistons
Ported Irons
Hyd roller
Stock Ported Intake
Assembled with Cometics yeilded 8.5:1 compression.

To get it to 9.5:1 my machinist said:
deck the block(0 deck), fly cut the pistons (to reduce the CC), and maybe mill the heads to attain the 9.5:1. I figured just order a custom piston but he said his way was cheaper. Now the reason for this is because the car will not see 93 octane anymore. Used 110 and meth all year. $70 for 10 gallons.:smile: Going to E-85 and meth next year. I have the fuel system to do this, turbo is a 70GTQ, and tuning with a TT SD chip, Wideband, and PowerLogger.

Now after doing some searches I have read that since I am using a Ported Iron that more duration on the cam may help. What size cam should I be looking to use? 210,212,218 or 224. I know the added duration will move the powerband up but I'm curious to see what is recommended. I dont want to use a solid roller since the hydralics make it well into the 9's and would rather not adjust valves repeatedly.

 

[bison]

Here is what I have now...
109, .020 over, 3 steel mains
Steel crank, rods and Diamond pistons
Ported Irons
Hyd roller
Stock Ported Intake
Assembled with Cometics yeilded 8.5:1 compression.

To get it to 9.5:1 my machinist said:
deck the block(0 deck), fly cut the pistons (to reduce the CC), and maybe mill the heads to attain the 9.5:1. I figured just order a custom piston but he said his way was cheaper. Now the reason for this is because the car will not see 93 octane anymore. Used 110 and meth all year. $70 for 10 gallons.:smile: Going to E-85 and meth next year. I have the fuel system to do this, turbo is a 70GTQ, and tuning with a TT SD chip, Wideband, and PowerLogger.

Now after doing some searches I have read that since I am using a Ported Iron that more duration on the cam may help. What size cam should I be looking to use? 210,212,218 or 224. I know the added duration will move the powerband up but I'm curious to see what is recommended. I dont want to use a solid roller since the hydralics make it well into the 9's and would rather not adjust valves repeatedly.

Id seriously reconsider your plans based on your above post. Id also look into other machinists since the rec your machinist gave is not a good one. The rpm you are able to achieve will depend on how much spring you can get on you heads and not the cam duration.

 

[rag231]

ideas

fly cutting pistons to reduce CC?? You fly cut pistons to aid in valve to piston clearance when you mill the heads. If any thing your cc size will increase. Also how much money and down time are you talking? Your engine will have to be disassmbled. Does your machinist have any of these combos out on the tracks or streets. Does he primarily work on Fords? ( just referring to the fly cutting piston terminology) Follow Bison suggestions or better yet employ his services.

 

[jasjamz]

Spring now is a Comp 941 installed at 145#@1.700 and 400#@1.152 what else do you need to know?

I have no issue just buying pistons. I guess he just wanted to save me money. He has done plenty of engines for turbo buicks, LSX and faster stuff. I want to be able to bump the compression up and take advantage of the additional octane. Bison, I see all the talk of bumping compression up and have the chance to do it now while its all apart. I could throw it all together and be back at 8.5:1 but why. Its not the engine in the car this is a virgin block and the rotating assembly I had from another engine.

Im sure I could sell the old ones since the were only used for a 1.5 seasons.

 

[Phoneguy]

Give Bobby at RPE a call, he can answer your questions and do the work if you want.

Bryan

 

[Dabigguy]

Can you tell us more about your combo? ....tires, rear gear, converter, fuel system.......what are your ET goals? The camshaft is the center of the total package.

 

[HP Man]

IHMO check with someone using such a combo and take their advice not some machine shop's that don't know the Buick Engine or it's requirements?
First, what are your goals in performance and building a engine combo that lasts should be your main concern? Personally I'm scared of how far you plan to push a stock block and building an bomb ready to explode! Guys do it but one false move or detonation and bye-bye your engine and transmission bell housing or DOTC Club? You have a very flimsy engine to start with, thin pan rains, thin main webs, and even with a block girdle a bomb waiting to go off! So consider these facts before throwing your money away building something lacking endurance? Buy your self a Stage 2 car and be done with it! Ask a Good Buick Expert as suggested? Gene

 

[jasjamz]

Can you tell us more about your combo? ....tires, rear gear, converter, fuel system.......what are your ET goals? The camshaft is the center of the total package.

Sure, M/T DR 275/60, 3.42, 9.5 ptc double Pumper with -8 feed. Et goals 10.0 on e85 and meth. Im sure there are going to be more people wanting to bump compression and take advantage of it. A thread like this is intended to help more than me. I'm just hoping the more experienced guys will chime in and give some pointers on cam selection when you add compression.

 

[TURBOPOWERED68]

i was/am also looking to bump up the CR up some. just not sure how much.
i will be going with a small cam tho.

 

[bison]

Spring now is a Comp 941 installed at 145#@1.700 and 400#@1.152 what else do you need to know?

I have no issue just buying pistons. I guess he just wanted to save me money. He has done plenty of engines for turbo buicks, LSX and faster stuff. I want to be able to bump the compression up and take advantage of the additional octane. Bison, I see all the talk of bumping compression up and have the chance to do it now while its all apart. I could throw it all together and be back at 8.5:1 but why. Its not the engine in the car this is a virgin block and the rotating assembly I had from another engine.

Im sure I could sell the old ones since the were only used for a 1.5 seasons.

Those springs are good to about 5800 with around .500 lift. More than that its a roll of the dice. If your building a 9.5:1 engine and want to make some power (like 800hp at least) you will be over 6000 rpm. New pistons should be ordered. Cutting pistons and deck is a no no unless they need to be for flatness or clearance. You never remove metal when you dont need to. Especially on a junk block that needs everything it has. My rec is to go to a S2 block and take advantage of the extra fasteners and strong bottom end that wont move around. You will have about $4k more into it but you will be much better off. If you dont do something about getting a better spring on the heads id leave the cam at 212/212 and remove gear and run a tall 29" slick. You may need to get the converter adjusted if you do that and really crank it up. Even with that you will need some considerable boost to get it to pull over 6000 rpm if you do have adequate spring on there. The 70GTQ will make power well beyond 30psi and 6000 rpm. Below 5600rpm/30psi its not the correct turbo for the job imo. You will wind up with a narrow useful window of rpm for performance if you run the 70GTQ where it should be run and only run 941 springs. The converter will likely flash to at least5500@high 20's boost and the valvetrain will be done at 5800 when you will need it to go to 6200 or so if you are running a high hp engine with a hyd roller. 5800 in 3rd with a really efficient converter with about 3% slip will net you about 136mph. 275/60-15 MT DR is only 27.3" tall so you will need to figure that in too.

 

[jasjamz]

Thanks! I appreciate the replies. On the 9.3:1 range motors you ran did you like any iron head, cam and Turbo combos you can recall?

 

[bison]

Thanks! I appreciate the replies. On the 9.3:1 range motors you ran did you like any iron head, cam and Turbo combos you can recall?

They all made good power over 25psi iron or aluminum heads but the spring issue is a problem with the iron heads. A lot easier to get a good spring on the aftermarket heads (14 bolt). It can be done on irons but i dont see the point unless you are restricted to running stock heads. Fwiw the 9.3:1 stock block made 413whp@12-13psi and, 523whp@17-18psi, and 687whp@24psi. I couldnt get the boost any higher that day on the dyno. I melted #1 when it was over 29psi in 3rd for about 3 seconds but it went 114mph in the eighth. It had over 800ftlbs@24psi too. Ive posted plenty about cams you can search for that info. The cam wont do crap for power by itself but if you are going to really turn it up and your valvetrain and bottom end can take it it will allow you to extend the rpm range a few hundred more rpm and give you enough to run several mph faster in 3rd gear. With out the boost larger cams will hurt performance.