Well, I am going to install and dyno as soon as I get it. I put down 187 and 265 stock. What do you guys think I'll put down with the intake? Take into consideration this will be my first mod, no headers, stock heads and cam. I'm wanting/hoping to see 210whp and maybe drop to 250tq.

Let's here the estimates.

 

im gonna say 195 hp and 275 tq ....i think if you add headers and other stuff it should make more ...let us know how everything goes

 

You aren't going to gain much just by swapping that intake. Do yourself a favor and at least put a cam in there at the same time. It still won't run at its greatest until you get headers, but you'll kick yourself later for not camming it now. The stock cam is designed to only make peak power around 4500rpm which is more than fine for a 305 TPI. I bet you won't have any more topend power than you would with the TPI. I was going to swap an LT1 intake onto my 305 at first and then I dove into the head swap too.

One thing I learned was that the stock exhaust manifolds KILL these 305 TPIs. I swapped to SLP 1 3/4" headers and my car pulls all the way to 5700RPM (highest I've taken it..don't wanna break a valvespring), with the stock, unported TPI setup. If you were to add headers and a cam at the same time, you'd feel a huge improvement, but just swapping the intake won't net you much at all. You might even get slower from the minor loss in torque. Before my headers, my car had NOTHING over 4600-4700RPM. Trust everyone when they say headers wake these cars up.

I'm hoping for a lot of power when I do my swap, but I'm putting on 52cc chamber aluminum LT1 heads (221/179@.500"), LT1 intake, CC304 cam, and I already have SLP 1 3/4" headers.

 

Okay, I am still confused on the L98 cam. If the LT1 cam can pull up to 5500 or so, and the L98 cam is only slightly smaller, why wouldn't it be able to go up that high too, but with a tad less power?

Please explain.

I am getting 3.42 gears to give me some digging power. Headers are next on the list, but I'm still up in the air about a cam.

 

Because the LT1 has much better heads and I believe the exhaust manifolds are a bit more efficient. The TPI intake is sufficient for an otherwise stock 305. Like I said, with the bone stock TPI setup and SLP 1 3/4" headers and my peanut cam, I can pull to 5700RPM. Headers will make the biggest difference. Then, with your LT1 intake swap, put in something like a 204/214 or a little bigger cam with around .470" lift. That will work with your stock heads and give a nice performance boost.

My CC304 cam has 210/220* intake/exhaust and .500/.510" lift. I'm going to have a higher CR though, close to 10.2:1 because of the small-chambered heads and the exhaust ports on the LT1 heads flow over 60% better than 081 castings in stock trim.

All I'm saying is that you aren't going to notice anything until you get headers installed.

 

The L98 camshaft is actually BIGGER than the LT1 cam. The L98 camshaft has 207/211 duration @.050", which is more than the LT1 camshaft at 205/207 @.050"

But, you do not have the L98 camshaft unless you have swapped cams before, or got your 305 out of a 305TPI/M5 car. If that is the original motor, then your camshaft specs are as follows.
Peanut Cam (non G92 305/5spd, and all 5.0Ltpi/auto)
Duration is 179/194 @.050" lift
Lift is .350"/.384" with 1.5 rockers.
Lobe sep is at 109.

This data came from the TGO tech data sheet. scroll down near the bottom for cam specs.
https://www.thirdgen.org/newdesign/tech/techdb.shtml

 

Ah true, all of the '91 cars (auto and manual) got the smaller cam unless you had the G92 performance package on your car, but I doubt that seeing as you said you are going to put 3.23s in. The G92 package would've given you 3.42s, N10 dual cats, etc.

Though I must say, that 187rwhp number sounds high to me for a stock 305 with peanut cam.

Either way, it's not going to matter what cam you have until you get headers. I was telling you to do your cam swap now so you don't have to pull the intake off later to put in a cam. Might as well put a little bigger cam in now that the headers will take big advantage of.

 

Headers are 3rd on the list for power. I'm thinking Hooker 2055's for headers. My birthday is next month

Now back to the cam, I do have the L98 cam, as do all SD TPI cars. How else would my car be able to dyno such nice stock numbers. Also, I was thinking of mildly ported aluminum Vette heads with stronger springs when I get the cash.

However, I am a beast of burden and I want to see what this intake does for a stock car. I'm giving that info to John McMillan and posting it on here. I think it will do people some good to know the cold hard facts. If indeed it does nothing powerwise, which might just happen, then my car won't be that way for long because I have those 3 mods (2055's, gears, and maybe those aluminum vette heads) coming to help it out.

 

The LT1 pulls to 5500 because of its short runner lenght...about 3.5 inches or so...TPI runner lenght is like 18 inches...it just dosen't support much past 5000rpm..LT1 heads are only marginal better then L98's....By modding the entire TPI intake as a whole...ie. runners /ported base/CAI youwill pick up some upper RPM 's but it still is a 2000-5000 or so RPM set-up. A full catback and headers on a thirdgen does add fairly large gains..the stock exhaust is just plain terrible. An LT1 intake on a 305 will just kill its bottom end... you would have to run a decent cam to take advantage of its RPM potential.Youi'll lose 30-40 lbs of torque and your peak hp gain will be next to nothing...though from about 4500 up you'll pick up a bit...right when your cam dies. I would keep the TPI set-up/put on the vette heads/headers/ mild cam swap/ and gears and have a very fun car for the street...also some intake /ignition mods...it would run strong. I have a 88 305 T/A that runs great with just bolt-ons...

 

Got a dyno sheet to back up that statement? I'd love to see it.

What I'm getting at is GM used a "LT1" intake on an engine smaller then the 305 5.0L V-8. They put a "baby LT1" in a Caprice. It was a L99 engine with a "huge" 4.3L V-8. The intake manifold on this L99 engine looks identical to the LT1 intake on the outside, only the ports are slightly smaller to keep velocity up.

That little engine moved the big a$$ Caprice fairly good considering it's weight. That requires TQ to move massive weight so your statement is defunct.

 

Most 4 bangers have a short ram style intake. They basically use a log style intake with about a 3 to 8" tube straight into the head.

The loss of TQ isn't nearly so crippling on a 305.

 

Well sad to report, this will take longer than planned. I had to back out of the sale because my car's AC problems. It's costing me more than I ever planned to spend and summer weather in AZ is a killer. So I had to weight this; $320 intake plus a few possible fitment issue headaches + numerous runs to the auto store - or - working AC? So I chose the AC. I still have my friends LT1 intake and I will work with that. But like I said, I'll post results when it happens, just don't hold your breath for now.

 

I hope my flowtech hedders are good enough , im bulding a 1986 305 tpi with a better cam , hedders wrapped with thermotech wrap , 3.5 inch exhaust , BBK AFR , airfoil , ported plenum and heads and i removed the cat and kn filters.
Now that should be a good combo right ?
Summit claims a 40-50 hp extra with that cam on a stock 1986 305 tpi.

 

http://popularhotrodding.com/tech/0803phr_beast/

That link has a dyno sheet that shows the drop in torque from a SuperRam to an LT1. It's not a 305, but the visual difference would be about the same. Going from a long to short runner will show a HUGE drop in torque. This might not effect the ETs on a healthy 350 or larger engine,,, especially if there are traction problems or you set the gearing and stall converter up for the short runner intake,,,, but I promise you if this guy was to swap out a "free mods" TPI (ported plenum, etc) with a LT1 intake on a stock 305 he'll be slower than an LG4 car.

 

I have seen and know about that link. I converted Toms intake for him.
I won't get into which is better, peak tq or flat tq.
[hint] flat tq carries you the entire 1/4 mile, peak drops off [/hint]

 

If the ports on the LT1 intake are larger than the ports on the 305 heads, the car is gonna run like a dog. That same logic applies to any head/intake combo.

Forget about torque, hp, yadda yadda. Anyone who suggests a long tune setup is better than a short runner needs their head checked. Peak torque loss isn't the problem with an LT1 intake.

-- Joe

 

To add to that if I was wanting to install a short runner intake on a 305 i would get a L99 intake, not a LT1 intake. The L99 intake has much smaller ports but has room to open them up if you replace your 305 with a 350+.

 

Do you have a dyno sheet that says the 305 won't lose torque?
Yes flat torque is more important then peak...but the cam in a stock 305 is built for low end grunt ..period...you put a short runner on it you will kill it. You put in a better cam diffrent story..(then there's the ****ty heads)

You can not compare a 4.3 motor designed to run with a short -runner intake that has diffrent heads/cam,(not to mention stroke/bore size ect.)to a 305 with heads/cam that were put on to run with the longtube runner intake designed for it. Two diffrent engines in two diffrent cars is a pointless argument.

 

No, I wish I did though. All I'm really saying is that it won't be such a big loss as people make it out to be. I would eat my words if someone does a straight L99 intake swap on a totally stock 305 and the bottom falls out. Any takers?

I once offered my conversion for free if someone proved to me they had the capability of performing such a test. They would have to provide the intake of course, I would only do the machine work for free. I didn't get many takers and NO ONE followed through.

 

I think it will lose some bottom end...as to how much,who knows..All I was saying is an LT1 intake on a 305 is a bit of a mismatch from a stock standpoint.
It would be neat to get a short-runner set-up to run well on a 305...and if the L99 has smaller runners and I assume bolts up just like a regular LT1 it might be decent. The biggest problem is everyone jumps to a 350+ because they are so easy to obtain,build...no-one spends enough R&D time on the 305's...