HP out of a twin plug 3.4L?

[GaryR]

Thanks Joe. I removed the carbs today to take the shroud off for refinishing and looked down the intakes into the head. Someone spent some serious time polishing down there! I pulled about a softball size of crap out from between the cylinders.. little nuts, twigs, big nuts, and assorted junk. Cylinder fins were gunked up from the mouse piss and both steel shrouds were rusted to bits. Luckily I have like-new ones from another motor that i'll bead blast/paint/reinstall. The fins cleaned up great with a wire brush and I was able to blow all the garbage out. Top of the oil cooler was half-plugged too but that seemed to blow out fine also.

[dfink]

Same basic setup only 3.4 with 10.5:1 pistons. I dynoed at 275 rear wheel. Given the slightly smaller displacement I would take a guess at 250 rear wheel. The short stroke should have different rev and torque properties however.

[onboost]

Originally Posted by joetiii

I will be building a similar engine this winter. I believe the MM 98mm P&Cs measure at 9.8:1. Though I have heard there are higher compression MMs. With a mod S cam and twin plug I would be conservative at guessing 265 horsepower.

You are correct in that the new motor will give you a a very noticeable shove

I have a motor/parts sitting on the stand as well with this config.. believe my pistons were 10.1 Though I have heard of some that are 10:5.1 as well.
I'll be running 46 MM TWM throttle boddies on mine.. still trying to decide on what cam. Car will be hot street/auto-cross/DE not dedicated track.

[jpnovak]

I have a 3.2SS that CC'd 10:1. Its twin plug with DC40-108 cams. I am running TWM itbs and EFI.

The car also has a short, close-ratio transmission and weighs about 2000#.

This motor is absolutely incredible compared with the stock 3.0. It feels like there is nearly as much torque around 2500 as the stock 3.0 but above 4K there is no comparison. It flat out hauls ass until 7200 when the rev limiter kicks in. You will love the engine combination.

I have not had the car on the dyno. Its on the list but too hot right now to subject the car to so much torture.

[CBRacerX]

I had a motor almost exactly like this and LOVED it.

[CBRacerX]

Are the heads early or late SC?

[onboost]

Originally Posted by jpnovak

I have a 3.2SS that CC'd 10:1. Its twin plug with DC40-108 cams. I am running TWM itbs and EFI.

The car also has a short, close-ratio transmission and weighs about 2000#.

This motor is absolutely incredible compared with the stock 3.0. It feels like there is nearly as much torque around 2500 as the stock 3.0 but above 4K there is no comparison. It flat out hauls ass until 7200 when the rev limiter kicks in. You will love the engine combination.

I have not had the car on the dyno. Its on the list but too hot right now to subject the car to so much torture.

Gary R.. not trying to hijack your thread, that being said...

So Jamie, what size TWM w/what # injectors? Which EFI?

So you're really liking the DC40-108 cams huh? That's my area of head scratch at this point.. trying to determine which cam will work best for this set-up.

My heads are large port 78, twin-plug as well.

Thanks,

Paul

[0396]

Sorry to hijack this , but I have a 3.4 built and I'm a little disappointed. I'm wondering on the jetting you folks are using.. Can you please provide me a 'base' line setting? I'm currently using 175 mains / 38 vents/ 155 air / 1 3/4 European / Monty twin / 35 degree advance ...suggestion?

[GaryR]

Originally Posted by CBRacerX

Are the heads early or late SC?

I believe they are from a 78 originally but they are ported out to 40mm now (and twin plugged of course).

[tomkirkcis]

Gary

I have a similiar engine. Same pistons, webers and twin plugs. Mine has GE60 cams, larger primary headers and slightly larger ports. I believe I have about 275 HP-280 HP.

It really depends on your cams. The GE60 is more agressive than S cams. If they are S, my guess is your engine is in the 260 to 275 range.

I am very curious what size venturis you have. I just ordered new 38mm venturis. I was tempted to try 40's.

By the way, I am just up the road in Northampton Ma

Tom

[GaryR]

Originally Posted by tomkirkcis

Gary

I have a similiar engine. Same pistons, webers and twin plugs. Mine has GE60 cams, larger primary headers and slightly larger ports. I believe I have about 275 HP-280 HP.

It really depends on your cams. The GE60 is more agressive than S cams. If they are S, my guess is your engine is in the 260 to 275 range.

I am very curious what size venturis you have. I just ordered new 38mm venturis. I was tempted to try 40's.

By the way, I am just up the road in Northampton Ma

Tom

Tom - I'm told they are 38mm venturis and they were used to give her a better midrange. The PO said she will pull like a train to redline, may get a little more top end out of 40's but mid-low range may suffer (according to him)..


Here she is about ready to go into the car, too bad the car isn't quite ready! I used all SS bolts for tin and nuts wherever possible.