305 TPI Set up (need more power)
Thread Starter
Junior Member
Joined: Nov 2007
Posts: 8
Likes: 0
From: Woodbridge, VA
Car: 85 Camaro Z28
Engine: 5.7
Transmission: 700r4
305 TPI Set up (need more power)
I have a 91 Z28 with the 305 TPI set up. I am trying to do some things to get a bit more power out of the car. I am trying to find out if changing the heads to the 350 IROC or L98 heads would make a big difference and also going with the FIRST TPI set up. I heard just that intake set up alone makes a big difference. I am just looking for help or advice as to what i can do with the enging i have int here without having to pull the motor since the botom end was recently done up. Also, changing the heads and the TPI set up to the better one, does this mean i have to get the computer tuned, or should it run pretty decent on the factory tune. And also if i change the heads and TPI to the 350 ones, does that mean i have to change the computer to a 350 set up?
Looking forward to replies.
Thanks!
Looking forward to replies.
Thanks!
Supreme Member
iTrader: (1)
Joined: Sep 2002
Posts: 2,565
Likes: 10
From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: 305 TPI Set up (need more power)
I don't think either of those are a good way to get more power out of a 305. L98 heads will drop your compression down quite a bit. Yes they flow better but that's not going to help you much if at all. The only worth while heads for the 305 are the AFR heads that were designed for the 305. Everything else is pretty much a waste of time. You can't make your 305 behave like a 350 in that manner. Additionally I think installing an aftermarket intake on the 305 is probably a waste of time and money. You'll just lose low end torque and you won't gain enough on the high end to justify the price. The TPI intake is restrictive on the 350, not so much on the 305. Siamesed runners, ported plenum and a slightly larger throttle body would be all you'd probably ever need on a 305.
If you want to make more power on a 305 I'd start with the cam. I don't know if your car is an automatic or not but the 305TPI engines after 1985 got the peanut cam and it isn't worth a ****. In later years at least the 305TPI cars got the L98 cam. The 305 can really use any cam the L98 can. So the LT4 hot cam would be a good bet. I don't know if that would be too wild for stock heads or not but it is something to consider. You could definitely pick up an L98 cam for next to nothing so that's a thought. Again I'd recommend the 305 specific AFR heads if you can find them and do some porting work on your stock TPI hardware. Slightly better injectors may be in order and you could benefit from an adjustable fuel pressure regulator. Not a lot, but some. Roller rockers would be a good way to go as well if you have your existing heads ported or you get some AFR's in there. None of this requires pulling the motor or touching the bottom end of the engine. As far as tuning goes any major engine changes will require tuning. However you will not need a 350 PROM for your 305. Ever. You could end up with a wild enough 305 to require a totally custom chip, but you are a ways off from needing that.
However what you'd spend on tuning and improving a 305 is really not worth it beyond the L98 cam or something like that. You get more for your money with a 350. I know people get tired of hearing this on these forums but this gets said a lot for a reason. 350 blocks are CHEAP. There is pretty much no reason not to go with one over a 305.
If you want to make more power on a 305 I'd start with the cam. I don't know if your car is an automatic or not but the 305TPI engines after 1985 got the peanut cam and it isn't worth a ****. In later years at least the 305TPI cars got the L98 cam. The 305 can really use any cam the L98 can. So the LT4 hot cam would be a good bet. I don't know if that would be too wild for stock heads or not but it is something to consider. You could definitely pick up an L98 cam for next to nothing so that's a thought. Again I'd recommend the 305 specific AFR heads if you can find them and do some porting work on your stock TPI hardware. Slightly better injectors may be in order and you could benefit from an adjustable fuel pressure regulator. Not a lot, but some. Roller rockers would be a good way to go as well if you have your existing heads ported or you get some AFR's in there. None of this requires pulling the motor or touching the bottom end of the engine. As far as tuning goes any major engine changes will require tuning. However you will not need a 350 PROM for your 305. Ever. You could end up with a wild enough 305 to require a totally custom chip, but you are a ways off from needing that.
However what you'd spend on tuning and improving a 305 is really not worth it beyond the L98 cam or something like that. You get more for your money with a 350. I know people get tired of hearing this on these forums but this gets said a lot for a reason. 350 blocks are CHEAP. There is pretty much no reason not to go with one over a 305.
Last edited by 87WS6; May 5, 2010 at 10:47 AM.
Supreme Member
iTrader: (1)
Joined: Feb 2000
Posts: 7,964
Likes: 4
From: Norfolk, VA. USA
Car: 86 Trans Am, 88 Formula
Engine: 95LT4, 305TPI
Transmission: T56, T5
Re: 305 TPI Set up (need more power)
L98 vette heads will make you a tad faster since it makes your car lighter.
The easiest and cheapest way is to add Nitrous to the car. 100-150 wet shot is safe.
The easiest and cheapest way is to add Nitrous to the car. 100-150 wet shot is safe.
Thread Starter
Junior Member
Joined: Nov 2007
Posts: 8
Likes: 0
From: Woodbridge, VA
Car: 85 Camaro Z28
Engine: 5.7
Transmission: 700r4
Re: 305 TPI Set up (need more power)
Thanks for the fast response.
Yea, i was looking at just getting better flowing heads on the 305 and also getting a nice decent cam, but the only problem i was running into thinking about doing that is, Will i have to get the computer tuned, or how can i get it all to work without the car running bad?
Yea, i was looking at just getting better flowing heads on the 305 and also getting a nice decent cam, but the only problem i was running into thinking about doing that is, Will i have to get the computer tuned, or how can i get it all to work without the car running bad?
Supreme Member
iTrader: (1)
Joined: Sep 2002
Posts: 2,565
Likes: 10
From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: 305 TPI Set up (need more power)
Supreme Member
iTrader: (1)
Joined: Feb 2000
Posts: 7,964
Likes: 4
From: Norfolk, VA. USA
Car: 86 Trans Am, 88 Formula
Engine: 95LT4, 305TPI
Transmission: T56, T5
Re: 305 TPI Set up (need more power)
Supreme Member
iTrader: (1)
Joined: Sep 2002
Posts: 2,565
Likes: 10
From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: 305 TPI Set up (need more power)
Trending Topics
Supreme Member
iTrader: (1)
Joined: Feb 2000
Posts: 7,964
Likes: 4
From: Norfolk, VA. USA
Car: 86 Trans Am, 88 Formula
Engine: 95LT4, 305TPI
Transmission: T56, T5
Re: 305 TPI Set up (need more power)
copied from LS1 Tech which copied it from Sallee Chevy
From Sallee-Chevrolet:
SBC Corvette Aluminum Cylinder Head Assembly (This is also the ZZ4 350 HO Cylinder Head).
This aluminum cylinder head assembly for small-block Chevrolet V8s is ideal for street rods, fresh-water power boats, and high-performance applications. GM Performance Parts’ aluminum cylinder head assembly combines the benefits of light weight, advanced design, and an affordable price. This complete head assembly includes valves, chrome silicon heavy-duty valve springs, retainers, 3/8” screw-in rocker studs-everything an enthusiast wants in a high-performance cylinder head package!
GM Performance Parts aluminum cylinder head assemblies are based on brand new Corvette light alloy castings (P/N 10088113). The Corvette cylinder head’s advanced design features include D-shaped exhaust ports that enhance the flow of burned gases, high-velocity intake runners that provide crisp throttle response, and centrally located spark plugs that improve combustion efficiency. Valve seat inserts for 1.94” diameter intake valves and 1.50” exhausts are installed in the 58cc combustion chambers. Raised rocker cover rails with machined sealing surfaces virtually eliminate rocker cover gasket oil leaks.
This high-performance cylinder head assembly is used exclusively on High Output 5.7-liter small-block V8 engines. Unlike production Corvette cylinder heads, it is outfitted with special heavy-duty valve springs (see part number 12551483 for technical specifications(JIM: These are the same LT4 springs as the Hot Cam Kit). A pair of aluminum cylinder heads offers a weight savings of approximately 50 pounds over comparable cast iron cylinder heads. (A bare aluminum casting, less valves and springs, weighs 19 pounds, versus 44 pounds for a bare cast iron head). This reduction in total engine weight of 25 pounds each can improve handling, acceleration, and fuel economy.
Part Number ... Description.
12555269 ......... Stamped steel rocker cover.
10229162 ......... Corvette screw-in oil filter cap.
12342056 ......... Chrome screw-in oil cap with GM logo.
12338092 ........ .Valve cover hold-down bolts (8 required).
14094717 ......... Hold-down bolt washers (8 required).
14088793 ......... Hold-down bolt gaskets (8 required).
14088564 ......... Neoprene rocker cover gasket.
12557236 ......... Composition head gasket, .051” thick.
12495499 ......... Head Bolt Kit.
12495490 ......... Rocker Arm Kit.
Technical Notes: This casting does not have intake manifold heat riser or EGR passages. The exhaust port exits are approximately .100” higher than production cast iron heads; exhaust manifolds and aftermarket headers may require modification to maximize airflow. The spark plug holes are angled; check for adequate exhaust manifold or header clearance. Use 3/4” reach gasketed spark plugs with 5/8” hex heads (AC FR5LS), 904, or MR43LTS. In Rapid Fire use #8 plug. Both ends of the head are machined for alternator, power steering, and air conditioning compressor mounts. No pushrod guideplates; use rail type rocker arms P/N 10089648. This aluminum head assembly requires valve covers with central hold-down bolts and extra-long bolts with washers. A composition head gasket with stainless steel fire rings is recommended to prevent galvanic action between the head and a cast iron engine block. This head assembly is the same as P/N 10185087, except valve spring and retainer change.
These heads respond well to modest porting and a good valve job. The ZZ4 will get to an easy 378hp/412trq with just this mod. These heads do not like to ping at all, and they do not like over a 150 shot - that and the hypereutectic pistons. The intake port can get close to 180 in size after porting. The D-port exhaust means you have to check your headers and header gaskets to make sure everything lines up OK and that none of the exhaust ports are blocked in any way with everything attached and tight.
The Felpro Head Gasket with the pre-flattened steel fire ring works great and adds a little compression.
David Vizard talks this head extensively, as well as porting instructions and pictures, in his book "How to Build & Modify Chevrolet Small-Block V-8 Cylinder Heads (Powerpro Series)". Great book!
SBC Corvette Aluminum Cylinder Head Assembly (This is also the ZZ4 350 HO Cylinder Head).
This aluminum cylinder head assembly for small-block Chevrolet V8s is ideal for street rods, fresh-water power boats, and high-performance applications. GM Performance Parts’ aluminum cylinder head assembly combines the benefits of light weight, advanced design, and an affordable price. This complete head assembly includes valves, chrome silicon heavy-duty valve springs, retainers, 3/8” screw-in rocker studs-everything an enthusiast wants in a high-performance cylinder head package!
GM Performance Parts aluminum cylinder head assemblies are based on brand new Corvette light alloy castings (P/N 10088113). The Corvette cylinder head’s advanced design features include D-shaped exhaust ports that enhance the flow of burned gases, high-velocity intake runners that provide crisp throttle response, and centrally located spark plugs that improve combustion efficiency. Valve seat inserts for 1.94” diameter intake valves and 1.50” exhausts are installed in the 58cc combustion chambers. Raised rocker cover rails with machined sealing surfaces virtually eliminate rocker cover gasket oil leaks.
This high-performance cylinder head assembly is used exclusively on High Output 5.7-liter small-block V8 engines. Unlike production Corvette cylinder heads, it is outfitted with special heavy-duty valve springs (see part number 12551483 for technical specifications(JIM: These are the same LT4 springs as the Hot Cam Kit). A pair of aluminum cylinder heads offers a weight savings of approximately 50 pounds over comparable cast iron cylinder heads. (A bare aluminum casting, less valves and springs, weighs 19 pounds, versus 44 pounds for a bare cast iron head). This reduction in total engine weight of 25 pounds each can improve handling, acceleration, and fuel economy.
Part Number ... Description.
12555269 ......... Stamped steel rocker cover.
10229162 ......... Corvette screw-in oil filter cap.
12342056 ......... Chrome screw-in oil cap with GM logo.
12338092 ........ .Valve cover hold-down bolts (8 required).
14094717 ......... Hold-down bolt washers (8 required).
14088793 ......... Hold-down bolt gaskets (8 required).
14088564 ......... Neoprene rocker cover gasket.
12557236 ......... Composition head gasket, .051” thick.
12495499 ......... Head Bolt Kit.
12495490 ......... Rocker Arm Kit.
Technical Notes: This casting does not have intake manifold heat riser or EGR passages. The exhaust port exits are approximately .100” higher than production cast iron heads; exhaust manifolds and aftermarket headers may require modification to maximize airflow. The spark plug holes are angled; check for adequate exhaust manifold or header clearance. Use 3/4” reach gasketed spark plugs with 5/8” hex heads (AC FR5LS), 904, or MR43LTS. In Rapid Fire use #8 plug. Both ends of the head are machined for alternator, power steering, and air conditioning compressor mounts. No pushrod guideplates; use rail type rocker arms P/N 10089648. This aluminum head assembly requires valve covers with central hold-down bolts and extra-long bolts with washers. A composition head gasket with stainless steel fire rings is recommended to prevent galvanic action between the head and a cast iron engine block. This head assembly is the same as P/N 10185087, except valve spring and retainer change.
These heads respond well to modest porting and a good valve job. The ZZ4 will get to an easy 378hp/412trq with just this mod. These heads do not like to ping at all, and they do not like over a 150 shot - that and the hypereutectic pistons. The intake port can get close to 180 in size after porting. The D-port exhaust means you have to check your headers and header gaskets to make sure everything lines up OK and that none of the exhaust ports are blocked in any way with everything attached and tight.
The Felpro Head Gasket with the pre-flattened steel fire ring works great and adds a little compression.
David Vizard talks this head extensively, as well as porting instructions and pictures, in his book "How to Build & Modify Chevrolet Small-Block V-8 Cylinder Heads (Powerpro Series)". Great book!
Thread Starter
Junior Member
Joined: Nov 2007
Posts: 8
Likes: 0
From: Woodbridge, VA
Car: 85 Camaro Z28
Engine: 5.7
Transmission: 700r4
Re: 305 TPI Set up (need more power)
Yea, i have heard about putting on the L98 heads on there. But since those are different heads, that would mean i would have to change the TPI set up with the different INTAKE bottom, right? And also, my biggest concern with doing this is that, would i have to get a different ECU to make this all work? I mean, i will on a later date maybe a year or two change the whole block and all with a nicer set up. For now, im just wanting to get a bit more kick out of this thing without having to pull the motor. This is the stuff i "wanted" to do but was curious as to if its possible.
1. L98 Aluminum heads (possibly worked for better flow)
2. Decent cam
3. Either the BBK or First TPI set up.
4. Full exhaust done, headers and all.
As i said before, my biggest concern is whether or not i would have to get an ECU or HAVE to get it tuned somewhere. Im not sure if there are any places near me that do tuning on these older 3rd gens.
1. L98 Aluminum heads (possibly worked for better flow)
2. Decent cam
3. Either the BBK or First TPI set up.
4. Full exhaust done, headers and all.
As i said before, my biggest concern is whether or not i would have to get an ECU or HAVE to get it tuned somewhere. Im not sure if there are any places near me that do tuning on these older 3rd gens.
Supreme Member
iTrader: (1)
Joined: Sep 2002
Posts: 2,565
Likes: 10
From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: 305 TPI Set up (need more power)
If you go with aluminum Corevette L98 heads then you will need tuning to delete the EGR from the ECM. You'd want PROM tuning anyway as you'd be making serious changes to the engine setup. Heads, cam, headers, and exhaust are all going to change things quite a bit. As for the intake manifold, it is the same whether you run aluminum L98 heads or the stock LB9 heads. Aside from the weight savings I don't think the heads will get you all that much in terms of gains, but that's just my opinion. The stiffer springs are a benefit if you go with a bigger cam of course but you could replace the springs and rockers on your existing 305 heads.
Thread Starter
Junior Member
Joined: Nov 2007
Posts: 8
Likes: 0
From: Woodbridge, VA
Car: 85 Camaro Z28
Engine: 5.7
Transmission: 700r4
Re: 305 TPI Set up (need more power)
So i take it that mine comes with the LB9 heads? Is it worth even getting those things worked for better air flow? I know summit sells certain cams for that Camaro that they say doesnt need computer tuning, so i guess those are very mild cams that prob wont even make a difference, right?
Supreme Member
iTrader: (1)
Joined: Sep 2002
Posts: 2,565
Likes: 10
From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: 305 TPI Set up (need more power)
So i take it that mine comes with the LB9 heads? Is it worth even getting those things worked for better air flow? I know summit sells certain cams for that Camaro that they say doesnt need computer tuning, so i guess those are very mild cams that prob wont even make a difference, right?
If you want a really mild cam that doesn't require tuning the L98 cam is probably what you want. I can tell you from experience that the L98 cam does make a difference. It will make the engine feel a little more "peppy" than it does now but it isn't earth shattering either. If you go with a bigger cam than that tuning will be needed to get the best results.
Thread Starter
Junior Member
Joined: Nov 2007
Posts: 8
Likes: 0
From: Woodbridge, VA
Car: 85 Camaro Z28
Engine: 5.7
Transmission: 700r4
Re: 305 TPI Set up (need more power)
The 5.0L 305CID TPI engine was designated RPO code "LB9". So whenever anyone talked about the "LB9" that's what kind of engine they are referring to. The "L98" is the 5.7L 350CID TPI engine. The LB9 cars that came with an automatic transmission got the "Peanut" or "Baby" cams. The 5 speed cars got the same cam as the L98 and consequently they were rated for more horsepower and were closer to the L98's performance. As for porting the heads, I don't know. From what I've heard in the past the only heads worth a buying for the 305 are the 305 specific heads made by AFR. I don't know more about it than that. I'm not even sure that is 100% correct.
If you want a really mild cam that doesn't require tuning the L98 cam is probably what you want. I can tell you from experience that the L98 cam does make a difference. It will make the engine feel a little more "peppy" than it does now but it isn't earth shattering either. If you go with a bigger cam than that tuning will be needed to get the best results.
If you want a really mild cam that doesn't require tuning the L98 cam is probably what you want. I can tell you from experience that the L98 cam does make a difference. It will make the engine feel a little more "peppy" than it does now but it isn't earth shattering either. If you go with a bigger cam than that tuning will be needed to get the best results.
Supreme Member
iTrader: (1)
Joined: Sep 2002
Posts: 2,565
Likes: 10
From: Texas
Car: 1992 Formula Firebird
Engine: 305CID (LB9)
Transmission: World Class T5
Axle/Gears: 10-bolt, 4.10 gears
Re: 305 TPI Set up (need more power)
It is easy. The problem is you have to invest in the tuning hardware and learn to use it yourself or you need to update your car to use a newer type of fuel management hardware/software. Painless and Holley both have solutions for this. They aren't cheap though. Another alternative is the Ramjet 350 setup from GM Performance Parts.
Again you can use the stock ODBI stuff but you'll have to do the tuning yourself or buy a chip customized for your car. I'd check the DIY/PROM sub-forum on the boards for more information.
Again you can use the stock ODBI stuff but you'll have to do the tuning yourself or buy a chip customized for your car. I'd check the DIY/PROM sub-forum on the boards for more information.
Thread
Thread Starter
Forum
Replies
Last Post
Sanjay
Engine/Drivetrain/Suspension Parts for Sale
1
Aug 12, 2015 03:41 PM
