I was just curious if anyone is running this setup or if it would even work together?

 

355ci with LT4 heads? Uh, yep. Probably a lot of folks here have LT4 heads on their 355's.

 

What numbers are you guys seeing with this set up? 1/4 mile times? NA
Is it pretty streetable?

 

It all depends on your Cam, head specs, gears you choose. There are a whole host of variables to what your asking. For a *stock* LT4 headed 355, your not looking at a whole lot more power than stock. Bigger cam, and some worked heads, will get you the power you want.

 

First you need to decide how much power you want to make and go from there, a set of ported lt1 castings will flow more than a set of stock lt4 castings and will be a lot cheaper, although if your looking for big power a set of ported lt4's or afr heads are the way to go.

 

With a 355 and LT4 heads done by a REPUTABLE porter with larger valves, you could hit 420-430rwhp with a hydraulic cam and still have decent street manners.

There are two stock bottom-end LT1s (350s, obviously) on this board that have reached near 450rwhp... both with hybraulic cams. One used AFR 195s i believe and the other is SAR2K, but i forget what heads he used. With a good, built 355 bottom end, some worked AFR 210s, and solid roller cam you could concievably surpass 450rwhp a good bit while under under 7k rpm. Some of the 383s and 396s (with standard 23* heads) have broken 500rwhp with SR cams, so i don't doubt you could hit 430rwhp with a 355 and HR cam.

 

I don't understand your question. Help me out here: a 355 is just a 350 with a .030 overbore which you would do during a rebuild to clean up the cylinders and use new pistons. Actually you get aout 5.3 extra cubes or 1.5% more displacement, and a tad more compression if you change nothing else. This could amount to a few% more torque/power. It should be very little different than having LT4 heads on a 350 LT1 engine.

If you mean converting a traditional (Gen I) SBC to LT4 (or LT1) heads, with the reverse cooling design, that's another issue. Maybe that's where you were going, Mantis.

"DrunkenMantis" ?? Interesting name. Was it something she ate?

 

They will work great on a 355. I'm running them on my 355 now..stillworking out tuning bugs but so far have made 458 and it was dieing up top while the graph hadn't peaked yet. You can see in my sig what I ran with these "issues". Get the heads done by a reputable porter and have fun with the car. I'm running 2.05/1.57 valves in case your wondering..but I also take the car to 7000..and soon to be 7000+ so that factored into our valve decisions.

 

I used the factory LT1 castings with 1.94/1.50 valves.
Steve...

 

That's even more impressive

 

95 bird, i aspire to have an engine like you have one day. What rotating assembly are u running?? I hate to steal the thread but there's no better time to ask BTW, I think an LT4 intake/ported head combo will work perfectly on a 355.


trav

 

Thanks man... amazing what small valves can do.

Quick96Z,
95Bird's rotating assembly has the following: stock crank turned .010/.010, Eagle H-beam rods, Ross custom pistons, with C&A rings.
Steve...

 

i really appreciate the info...thanks buddy! Stock crank spinning to 7 grand, I learn something new every day. So it's possible to build a badass engine making 500hp, and still save some money by using a stock crank and just having it cleaned up. thank you. I am just trying to learn as much as I can, i plan on a 355 build up next winter.


trav

 

I would just upgrade the stock crank with a cast eagle/scat or something

just so i wouldnt have any 'stock' parts left lol

and it'd be new

 

This is an interesting thread. Very similar to the setup I will have complete on my '95Z before the end of spring. Although because of many variables and the difference many different combos run, I opted to consult the manufacturer I am doing business with on the biggest component/variable in the engine setup equation: The heads.

In my case, I am going with a recommendation from AFR directly, LT4 195's, 58cc, 2.02/1.60 valves, part number 1031's.

They came up with this combo due to what I told them I would be running, as this is going to be a fairly mild setup, that will see both street and strip time, but isn't driven often (it's my fun car)

30lb injectors
255lph walbro
LT4 intake port matched to 58mm tb
accel 300+ ignition
355 rotating assembly, forged crank & 10.5 pistons
ATI street damper - plan on spinning to 6500rpm
4-bolt LT4 block from wrecked Grand Sport Vette
LT4 Hot Cam, HD Timing set
Crane 1.6rr's
Comp R lifters & Hi-tech pushrods
Canton Oil Pan, HV pump & pickup

Car is a '95Z, 6-speed w/Mcloud street twin, 4.10s & soon to be 12-bolt 4.11's. Stock weight for the most part, looking for 11-anything on above combo.