coppercutlass

Ok so here is my dilemma . My current 355 has been a very reliable combination for the last 2 years. Putting on many street miles and 1/4 mile passes while gaining lower e/t's as i wring out every ounce of power i can from my combo. I have a 355 thats almost done. All i need is pushrods and port match the intake. But the more i think about it ., I really want to take the ported heads off and and put them on my current 355 thats in the car and build a turbo 355 with bbo heads and about 10 psi of boost.

The current goal is to put my current 355 as it sits into the low low 12's and i think we are on a straight shot to make it happen. shedding over 100 lbs , new fuel pump , and much needed looser stall with a so far best e/t of 12.45 i think we can do it.

I think we can achieve 11's with the ported heads on the same short block with a mechanical flat tappet cam and a custom tailored carb.


Should i finish the 355 on the stand or keep improving the one i have been running for a while which still has great oil psi and runs great. Im really liking the sound of a boosted EFI sbo. Sounds better than going to a BBO.

young olds

I vote turbo

stevengerard

my DD is boosted, I'd love to have a turbo olds.

coppercutlass

Just need BBO heads and a cam the rest can be done on the cheap with the right parts . Young olds i know you did a boosted 350 I think. Care to share what you did. Not so much cam specs but what items where used for your plumbing setup etc etc.

young olds

I bought some reinforced silicone couplers with a 3" mandrel bent charge pipe to go from the turbo to the intake, no intercooler. currently im running stock manifolds and crossover pipe, the outlet on pa side manifold has a 2.5" pipe to turbo then 3" exhaust off turbo that splits to dual 2.25" exhaust. im running an extreme velocities hat with a 1" spacer welded to the bottom. tial 50mm blow off valve. oil feed is off port on front of block, return line goes straight to the pan. i have a standard pvc valve in one valve cover that acts as normal while cruising with a one way valve o hold boost back. other side is vented to intake side of turbo to allow filtered air into engine then in theory under boost the air flowing through should create a vacuum affect to pull air/pressure out off crank case, essentially taking over for pcv under boost. https://classicoldsmobile.com/forums...-66-f85-3.html iirc it cost me about $1500, with meth injection, to turbo my already built and running engine. high cost items are turbo, a nice(tial) bov and meth injection everything else is relatively cheap. i did all the exhaust myself just paid for the pipe and went to a shop with a welder and a pipe bender on a sunday.

young olds

btw i wish we were closer, always wanted to run mine against yours. feel like our cars have been pretty comparable in the 1/4 mile.

coppercutlass

Im not complaining about the driveablity of my olds but im going to guess your car probably drives alot like a stock set up compared to mine. I think if i can get my car into the 11's it would be about as borderline what i think many would want to deal with street behavior wise. I would like to run 11's and have it purrrr like a kitten. I love the lumpy sound of a big cam but i can run less converter , less gear , less of everything and have the same e/t with boost.

oldsmobiledave

Chassis Dyno tune the car then go run it again. I'll bet you find at least a 10th in tuning.

coppercutlass

I would go that route if i was really desperate for that one tenth. I know where i can gain tenths but im dancing around things like keeping it a 3 series gear and I finally caved in and going to a 3200 stall. That will net a good gain , Since im in the process of redoing the body work i went ahead and planned a diet. I took the impact beams out of the doors after re skinning the doors , doing glass hood and deck lid .

Our first trip to the track will be to see how much we gain with the weight loss. that should be a little over a tenth. It will get a new fuel pump too.On the big end it drops big time and labors in the RPMs . So with those two things i should see some gains. Then the converter , ported heads , and solid lifter cam to further lower e/t . I think 12.0 is totally realistic

Im not complaing about my gains .Our first time out with this combo my best e/t was a 13.09. last time out was 12.45. I did alot of minor changes "tuning" I still have not really tapped into its full potential. I could do 4.33 gears and a 3400 stall but i still do alot of street driving and to me a 4.33 on the street is no fun.

I just have been wanting a turbo build for some time now and i think its time to pursue that route and have the best of all worlds.

Rallye469

So lets say you finish the 350 Olds on the stand that you're currently building...
How fast do you expect that to go?

Next question:
How fast do you really want go when all is said and done?

I think you'll want to go where the turbo will put you. But that's just my guess.
Get on it!

coppercutlass

Well if i finished the 355 on the stand i think 11.80's on street trim would be the goal. I think we can just sneak into the 11's with the ported heads on my current short block with some work. If i built a turbo sbo i think the goal would be bottom 11's.

young olds

I meant back when you were low 13's high 12's and I was na, I'd be sad if I lost with our current setups were matched, not that yours doesn't run hard. And yes I consider my engine very mild, it's my daily driver

coppercutlass

What did it run at the track i remember you got it out.

Kennybill

My vote is put the better heads on the engine in the car and change any corresponding parts aka camshaft, intake, carb while you're there. Then build the new engine into a turbo engine at your convenience as money lets you. I put my alternate on a toggle switch, turning it off as I staged. Every little bit helps.

61Bat

I second this! Amazing what you can learn about your car on a chassis dyno. The next best thing to full data logging on the track IMO and much cheaper. Show up at the dyno just like at the track w extra plugs, jets etc. Make a baseline and then any changes you make you can quantify the gains/losses.

coppercutlass

Im not serious enough to do dyno testing although i know its a very useful tool. Im yet to make a change i have not gotten a gain from. The plan at the moment is to still maximize what i have with the ported heads and cam. BUT i have a 355 thats ready to go besides the one in the car. Which i should finish but i think that short block will work better for my boosted build i think. I pretty much have a 355 thats ready to go in along with the one in the car and a spare th350. i got back ups and usually will tear into them for parts. The th350 i have as a back up i had built and then tore it apart to steel parts for it when my current th350 decided to loose 2nd gear due to a broke seal ring. i took the sealing ring from it along with the hd sprag unit from it then re rebuilt it with better parts. I tend to re rebuild things before they are even used sometimes.

oldsmobiledave

I can't think of someone who would benefit more from a dyno session than you. You are exceedingly serious about making your combination go faster. Take it from those of us who use the dyno often....spend the money.