So it's time for something different. 408 iron block LLSR set to shift at 7500 with my current dart 225 cathedrals ports and ported msd intake
Ls3 block 416 but hydraulic roller shifting at 7000 . Same heads and intake.

Current set up is sbe lq4 with dart 225 and msd intake. F14 cam shifting at 7200 rpm .
200-4r transmission and 8" fti converter with trans brake. 12 bolt Moser with 4.10 gear. I have both 275x50x15 et street r and a 275x60x15 pro radial. 26" are a tenth quicker due to extra gear.
Best et is 10.91 @122.8 with 1.45 60ft. At 3850 lb race weight.
It may not seem like it but the car is very street friendly. Fully loaded with leather and ac . Non lock up 8" converter cruise rpm is 2850 at 72mph on the 26" tires. Avg 20 mpg highway on long drive. I run this car as i drive it. Through basani tru dual 2.5" exhaust all the way to the back. Flows really well for 2.5" but if it becomes a restriction I will do cutouts.
On dyno graph, top line is msd vs fast 90 intake. Msd carries better so a solid will do well.
So ls3 416 lose 110 lbs and add 8 cubic inch extra or stay iron block and spin more rpm? Cost is close to same since hydraulic cam and valve train will be less expensive.

 

 

Lose the 100+lbs and go aluminum. You can always swap the cam and valvetrain later if you decide too

 

So another option I'm fond of is a 427 ls next shp block. I don't mind the weight as its already there and will make up for it with hprsepower.
meaning wheni went with the 6.0 lq4 with same heads and cam as was in the ls1, i dropped from 10.6 to 10.2 compression and still picked up hp/tq.
441/410 ls1
452/422 lq4 and was a tenth quicker.

I like the shp block since the longer skirts work better for strokers.

 

sounds like you already know what you want.
IMO Id go aluminum

 

Can't go wrong with the LS next!
Man if I had the cash to spend on my projects, this is up there on the list. I'd go for a big bore stock stroke for my TT GTO.

I say go with that or the AL LS3 if it's essentially the same as the iron block. The weight is worth it at this point in your ET goals. And you know the LS3 block is an outstanding platform, too.

Good luck either way you go, sounds like you got it figured out.

 

if i stayed stock gm block I would go ls3 . I realize people do 4" stroke all the time but I know it's still coming out the bore at bottom more than it should. This is not something I want to have to replace anytime soon and this shp block is literally $500.00 more than a ls3 block.

Going from an iron 6.0 to an iron 427 is a big jump so I'll make up for the weight in cubic inches.

 

Just went from a 6.0 iron to a 7.1 aluminum block lost 200lbs between the engine,intake and nitrous bottles. make the same power on motor i did when i was on a 250 shot, i think youll be happy with a 427 even if its iron plus youll already have a capable engine to build more off of. go dart my vote

 

thanks for the reply. I think so as well, those cubic inches along with being an iron block will make up the 100 lbs

 

I am selling the darts and going with some sps 245 cathedral ports. I was going to go square port and kicked it around hard but in the end, staying with a good cathedral for that power under the curve .
I already have an msd intake that's ported and really don't want to start over on everything, will update this as things happen.
Chad.

 

Sounds like it will be fun either way!

 

Well at last minute when ordering heads and talking with Gaven at SPS. I decided to go square port.
since I first started looking to do a build , I wanted to go low lash solid roller and with the cathedrals I was just gonna go hydraulic roller.
so I ordered up his ls3 heads with springs for llsr and pushrod holes drilled for 3/8 pushrods.
I will he selling my ported msd carhedral intake and going with the Holley sniper intake

 

Is that a normal race weight for a 408 Iron setup?

 

my car is full weight and fully loaded. Nothing's taken out.
added a 12 bolt Moser rear end with 33 spline axles as well.
3580 without me and 3845 with me. I'm 265ish

 

Dude, I don't have near the motor/performance knowledge some of these guys do but if you can get subtract 200lbs its like adding a good amount of power.
Unless you want the creature comforts, but taking about 100 lbs to 150 lbs should be doable.

 

3680 + 265 = 3945

 

Sorry. 3580 without me . Typo

 

I know it is, I could take some things out but not much before I start looking gutted .
I do race it but it's a cruiser before anything

 

Add a blower or turbo to your current engine.

 

that's not for me. I prefer a clean engine bay not cluttered up and instant throttle response of a NA motor. Though im aware the guy with the turbo junk yard 5.3 will most likely wax my *** , its just not what I want in this Car, I bought it new and don't want thrown together parts in it.