85T/A350

I am about to start the build for my 1987 Trans Am. The car has the 2.73 rearend. The engine is a 350 vortec out of a 96 Tahoe. Before I tell you the plan, this is my goal for the car:

Fun weekend car that has some power and will be fine on 70 mile trips. Im not building a drag car, might do some highway runs every once in awhile but thats about it. I would be happy with around 300 or so fwhp.

This is my plan:

1.Hypereutectic Flat 4.030 pistons
2.Quadrajet 750 Carb
3.Edelbrock Performer Intake
4.Comp Cams XR258HR cam
Specs(http://www.compcams.com/Company/CC/c...?csid=185&sb=2)
5. Hooker Comp Shorty Headers

This seem like it would make a fun street build for the weekends?

Shadow Z

iTrader: (2)

I'd say yes, since you're keeping the cam real mild, seeing as it has 2.73's out back.

Personally though, I'd go with forged pistons, incase you ever want to run a small shot of nitrous for a little bit of extra power. I mean, you'd get sick of like what, 240 RWHP tops?

I'm already bored with that amount of power with the Mustang, which is why I'm planning a single turbo build, already have a T56 swapped in to handle it, and aiming for 400+ RWHP. Won't be a drag car either, just a really, really fun street car. Keeping the full interior, radio, heat, A/C, everything down to the power leather seats.

DeltaElite121

2 valve or 4 valve 4.6? That's a VERY large demand on that motor if it's not a 4 valve 4.6, even if you had worked PI heads.

85 - that cam is TINY and I think you'de be disappointed. Give your heads a cam that can take advantage of it's power potential. I suggest you get a cam with high 22x or low 230's duration @50 with high(er) 400's lift, and longtubes. Hypers are fine for the street. Forged are a waste of money unless you intend to really stress the motor out.
Look at the roller equivilent to the XE268, or I'd recommend getting one from Lunati's lineup. I like their shelf cam grinds more, personally. Don't forget you'll need new springs for a larger profile cam.

Shadow Z

iTrader: (2)

Not really.......

On3 Performance has made 440 RWHP and just a hair under 500 RWTQ @ 10 PSI on an otherwise bone stock 2002 GT, stock 2V heads. They have over 10,000 daily driver miles on it, ran normally at 6 PSI.

Even a non-intercooled Vortech V2 setup will make 350+ at the wheels on a 2 valve. There are automatic guys that are making around 400 on the stock engine. 375-400 or so RWHP @ 8-10 PSI is just about what a 2 valve 1999-2004 GT will safely handle before you risk blowing the stock short block. Some have made close to 500 at the wheels, however, only to have their engine go kaboom in a matter of months.

4 valves really only show their flow advantage over a 2 valve in N/A form, such as with most notably the 2003-2004 Mach 1, then there's the 1999 and 2001 Cobra. When forced induction is involved, it's pretty much whoever has the strongest internals, wins.

Better head flow won't stretch the limits of the 1999-2004 GT engine's internals. Their rods are the weakest link, pistons will take their fair share of abuse, and some have had the stock cast crank up to around 600 RWHP.

A good example of this is the 1999 & 2001 Cobra. They won't handle much more power on stock internals than a 1999-2004 GT. Typically 500 at the wheels is right where they'll go, around 450 is starting to stretch the limits of the 2V 1999-2004 GT engine.

This is why the 2003-2004 Cobra makes crazy power on stock internals. They were built for boost from the factory. Sure they have the slightly better flowing 4V heads, but they also have a forged steel crank and Manley rods sitting in them.

EDIT: And of course it's a PI engine, it's a 2001 GT. PI engines came along with the new edge Mustangs in 1999. My stock PI heads with a single turbo setup will allow me to hit 400 RWHP at probably right around 8 PSI.

Shadow Z

iTrader: (2)

Also, there are some huge differences between the few different 4 valve heads made throughout the early 1990's until now. It's just not feasible to base an engine's strength on what it's heads flow, when the sort of power I want has been made over and over on stock short blocks.

I'll be fine though. I'm looking around for a spare '01-'04 2V GT engine right now incase I blow mine later this year, so I have something to immediately swap in, and next year I'll be talking to Modular Mustang Racing about one of their short blocks.

Eventually I really need to do something with the IROC. I've just wanted a Mustang for so long that I want to baby it now and put a few grand into it.

85T/A350

I forgot to mention springs, I think ill be using LS6 springs. Would that cam be alright with just those springs or will I need to have the heads machined for it? WIll that cam be alright on stock torque converter for awhile?

What about this cam? It has an power range equal to the intake I want to use and its quite a bit larger than the 258. Its the XR270HR.
http://www.compcams.com/Company/CC/c...?csid=187&sb=2

DeltaElite121

That's better. Match it to your intake and you'll enjoy it much more. As far as the LS6 springs - I've never used them so I can't say much about the characteristics of them. Just make sure if you're using new springs they cover the lift you need AND some just incase you decide to make rocker changes or something like that. That's how I did it, and I'm glad I did because I ended up stepping up to 1.6 RR's. Stock converter will work, but if you want a little extra bang in your step you can buy a higher stall converter for it. What trans do you have?

DeltaElite121

We have an On3 dealer down here and it's very common to see those kits running on Mustangs of different years (I had one). The general mark I see is 320-350RWHP on 2 valve's around here, but that's most of what I've seen. Doesn't mean I've seen everything, though. Internals will need to be changed regardless, so that's a given if you want it to last.

85T/A350

I have the 700R4. Will I need to have the valve guides cut to handle the lift or will I be fine with the new springs?

five7kid

iTrader: (14)

You'd be fine with your first choice of cam. It will have very nice low-end torque, and you won't need to add stall to the converter to use it. It'll cruise 70 miles a lot better with 2.73 gears than the XR270 will. The XR270 will feel like a dog going up hills, for instance.

You won't need to machine the heads to do the LS6 springs. You will need retainers that are different from the Vortec valves and the LS6 valves. Personally, I'd machine the guides in order to be able to use better valve stem seals, but if you want to avoid expense, the LS6 springs will work with Vortec seals.

Shadow Z

iTrader: (2)

Never knew that. Here I was thinking that a stock GT engine is indestructable, and could withstand more HP than what a top fuel dragster makes.

That's why I mentioned an MMR short block. They have short blocks that'll handle anything from I believe 600 RWHP on up to 2,500. I believe their strongest long block is good for 1,100 RWHP. Much more power than I'll ever want out of the Mustang.

Also, how in the world is the extra insurance of forged pistons a waste of money? Why don't you worry about actually researching the stuff you speak off, instead of trying to contradict whatever other people are saying.

As an example for you, KB's 350 hyper pistons range from $214.99 to $379.99. Their forged 350 pistons range from $419.99 to $469.99. Woooo! A whole 255 dollar price difference at the absolute most! That's some MAJOR cash right there, better stay away from them forged pistons.

A 1999-2004 Mustang GT's internals will pop at barely over 300 RWHP, forged pistons are a waste of money. Who would have guessed. It's always better to overshoot your goals and have room to improve, than to do it again. Ever noticed that trend when it comes to auto manufacturers? A 5 speed 1999-2004 Mustang GT will typically put down about 220-230 RWHP bone stock. They'll handle double that before they go.

The 2003-2004 Cobra is slightly underrated at 390 crank horsepower, and their stock internals have tolerated an insane 800 RWHP. Doing it right really leaves a lot of room to improve. Same exact deal with the LS1 and LS7. STS rear mount turbo C6 Z06's were making 600+ RWHP on stock internals the last time I checked. LS1 cars hit the 400 RWHP range with no problem.

85T/A350

Not to be rude, but can we stay on topic and discuss the Mustang situation elsewhere? Thanks

And Five7, I think I will go with the 258. The 70 mile trip Im talking about has several hills. The trip is to college which is in a town that is nothing but hills, many of which are pretty steep. I can go bigger on cam at a later time when I can get a decent torque converter.

five7kid

iTrader: (14)

Keep the discussions 3rd gen, please.

(Comparing 'Stangs to 3rd gens doesn't count.)

Shadow Z

iTrader: (2)

Shouldn't have gone off topic in the first place........... Thanks.

Shadow Z

iTrader: (2)

Also, that was incredibly mature. You attempted to tell me what a 2 valve can handle, then talk about being on topic. Good one, kiddo! Got me there!

I used it as a power example, and originally kept right on the topic of his choice for an engine combo.

85T/A350

I have said absolutely nothing about 2v or anything of the sort. You have me confused with the other poster. Deltaelite is the one you were discussing the 2v and Mustang info with.

Shadow Z

iTrader: (2)

Uh oh. I apologize. I could have swore that you were the delta guy.

I had just re-read his post that was commenting on the use of forged pistons being a waste.

85T/A350

Its all good, simple mix up lol. But, as to my topic, do you think the 258 would be better suited right due to long trips with hills and stock converter? And letter on go to something like the 270 when I change torque converters?

Shadow Z

iTrader: (2)

I personally wouldn't go as high as the 270 for something that's going to be just a fun cruiser. Apparently the 270 is the biggest recommended for a stock torque converter. I just wouldn't push it though, because being upset with the driveability of something can really just ruin it.

I've seen way too many people make awesome power on just the stock cam(s) for it to really be worth it IMO, regardless of the vehicle. Whether it's a high compression setup, nitrous, supercharged or turbocharged, or just a really well setup bolt on car.

If it were my build, I'd go with higher compression, and keep the cam mild, so you can still actually let the heads breath to their potential.

85T/A350

Yeah I dont think Ill go as big as 270 at this time. They have a XR264 that is between the 258 and 270. Would that be a good choice or would the 258 still be the best choice. Also, Im not tied down to Comp cams, its just what Im familiar with at this time. All suggestions are greatly appreciated.

Specs for 264 (http://www.compcams.com/Company/CC/c...?csid=186&sb=2)

DeltaElite121

I didn't see the 2.73's. I actually agree with you on this, then. That 270 isn't going to like the rear end gears unless you plan on switching them for best performance. You COULD probably find a nice 3.42 set for cheap off of here if you were looking for a change, though.

Shadow - just because you have forged doesn't mean everything. It's not the end of all ends. I'd rather have a GOOD hypereutectic piston than a cheap forged one. Each of them have plusses and minuses to them but you start seeing that dissipate when you get into the more expensive forged pistons (like Mahl's design, for example). I have forged pistons in mine only because I got a good deal on the longblock. They are a waste of money because I don't plan to use nitrous, I don't plan to boost it because I'm sitting at a higher compression, and I shouldn't be playing with these things anyways if I'm worried about pinging and shattering something because that obviously means I'm not paying attention to what I'm doing if that were the case. Case and point: OP wants a fun driver, not a strip runner. He doesn't need forged pistons to do that, even if he were to run it at the strip every weekend.

Shadow Z

iTrader: (2)

LSA looks a bit small on that cam. Typically a wider LSA will provide better driveability. Here's basically a general idea of things.

http://www.compcams.com/technical/FAQ/LSAproperties.asp

It's usually tough picking a good cam for what you want out of it. Exact reason why I'll go FI before I worry about being choosey over a cam, and relying on a particular cam for big power gains. That's what I'm doing. Going turbo and keeping the stock cams.

I've always thought it'd be neat to twin charge the IROC. A centrifugal and turbo. I was considering a cheap N/A setup so I could get it back on the road sooner, as in before 2013.

85T/A350

I'll be alright with a ride that isnt perfect. I can handle some roughness to it. Believe me, If FI was an option Id be all over it lol. But that wont be there till I finish my last 2 years of college. Just a fun weekend car is my goal for now. Can always upgrade bigger and better later. I think my original plan will be satisfactory for awhile anyway lol. Now my question is what kind of CR will I be looking at with the vortecs, flat pistons, the 258 cam, and a basic head gasket? I really do appreciate all the help.

five7kid

iTrader: (14)

Talk to Comp. I'm sure they'd custom grind a different LSA for you.

Shadow Z

iTrader: (2)

Well, what's your budget? You'd be surprised what you could afford if you shop around for used parts on forums. I've already saved a few grand by picking up a used rebuilt T56, used clutch and flywheel, used short throw shifter and aluminum driveshaft, used offroad X pipe, used bumper. Works as good as new. Matter of fact better, since my T56 was rebuilt with billet shift keys, new carbon synchro rings, and a 26 spline input shaft.

Vortech and Procharger head units pop up incredibly cheap all the time, which would be the easiest route, since turbos would require the turbo headers, probably a custom downpipe.

I think the only things I bought new were just the SCT tuner and a new pilot bearing for when I was having the T56 swapped in.

85T/A350

We got the engine back from the shop an it didnt need bored so we will be using the stock pistons. To my understanding a stock vortec cr is 9.5-1. What head gaskets could I get to maybe bump that up some? Also, I think I am set on the XR258HR.

five7kid

iTrader: (14)

You don't use head gasket thickness to manipulate CR. You use the correct head gasket to get the proper quench. Measure the distance from the top of the piston to the block deck (with the piston at TDC, obviously). Add the compressed height of the gasket to total 0.040" (plus or minus a little). For instance, if the piston to deck is 0.025", you want a head gasket that is 0.015" thick when compressed. Similarly, if the piston to deck is 0.000", you want a head gasket that is 0.040" when compressed.

You alter CR with piston dish/dome and/or combustion chamber volume. Since you're reusing your pistons, that leaves you with adjusting the chamber volume (as in, shaving the heads). But, I'd let it go if it's at 9.5:1 now.

85T/A350

Ah, I misread then. Thanks for all the help. Ive got the springs and retainers now. Looking to order a cam in the next little bit. One last question, will it be worth it to step up to the XE264 or will it kill my bottom end with my 2.73s? Im almost completely set on the 258, just getting one last recommendation. Also, Im not limited to comp if anyone has any other suggestions.