When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
What am I looking at for HP out of a vortec 305 tpi?
Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
What am I looking at for HP out of a vortec 305 tpi?
I have a chance to get 059 vortec 305 heads for free. I have a spring package I could use. I can also machine pockets or the valve guide bosses down for more lift. I can pick up a used SDPC vortec base and a comp cams 08-502-8 cam 218/224 @ .050 and .495"/.503". I have larger injectors in a box.
All told I would be into a vortec 305 with a cam for about $700 on my fresh 305 bottom end.
What's the horsepower outlook for that combo?
Last edited by 89fast5oh; Sep 20, 2020 at 01:00 PM.
Re: What am I looking at for HP out of a vortec 305 tpi?
I just purchased a set of L30 Vortecs (12558059s) myself. I plan to put them on top of my 60k mile L03 short block, with a GM 94666492 / CRANE CAMS COMPUCAM 2032 (214/220 @.050 and .452/.465" lift) with the Rochester TBI bored, shaved, spaced, etc. with 350 injectors on a Vortec carb intake. With a few other goodies, I'm not sure what to expect. I look forward to reading what people think yours will make. Not many builds out there using these heads, but with a lousy plastic truck intake, exhaust manifolds, and modest Vortec cam, the L30 made 230H.P. at 4600, and 285 lb.ft. of torque at 2800. It's hard to imagine that with a better intake, better cam, and better exhaust that you can't be pushing 275/280H.P. 50 horse from a cam, intake and headers? Is that reasonable? With the slightly more aggressive cam you have selected, maybe even a little more.
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by DynoDave43
I just purchased a set of L30 Vortecs (12558059s) myself. I plan to put them on top of my 60k mile L03 short block, with a GM 94666492 / CRANE CAMS COMPUCAM 2032 (214/220 @.050 and .452/.465" lift) with the Rochester TBI bored, shaved, spaced, etc. with 350 injectors on a Vortec carb intake. With a few other goodies, I'm not sure what to expect. I look forward to reading what people think yours will make. Not many builds out there using these heads, but with a lousy plastic truck intake, exhaust manifolds, and modest Vortec cam, the L30 made 230H.P. at 4600, and 285 lb.ft. of torque at 2800. It's hard to imagine that with a better intake, better cam, and better exhaust that you can't be pushing 275/280H.P. 50 horse from a cam, intake and headers? Is that reasonable? With the slightly more aggressive cam you have selected, maybe even a little more.
Marine 305 Vortec was net rated 260 hp and 310 tq. 196/206 @ 0.050, .431/.451 lift, 109 LSA cam.
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by Fast355
Marine 305 Vortec was net rated 260 hp and 310 tq. 196/206 @ 0.050, .431/.451 lift, 109 LSA cam.
My heads came off of a marine engine, actually. I missed out on the shortblock. Was that a TBI motor?
So again, in my case, a slightly warmer cam (but not by much), SLP headers, N10 and Borla catback...275 is not a crazy number? And maybe a little more for the OP, who has slightly more cam yet?
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by DynoDave43
I just purchased a set of L30 Vortecs (12558059s) myself. I plan to put them on top of my 60k mile L03 short block, with a GM 94666492 / CRANE CAMS COMPUCAM 2032 (214/220 @.050 and .452/.465" lift) with the Rochester TBI bored, shaved, spaced, etc. with 350 injectors on a Vortec carb intake. With a few other goodies, I'm not sure what to expect. I look forward to reading what people think yours will make. Not many builds out there using these heads, but with a lousy plastic truck intake, exhaust manifolds, and modest Vortec cam, the L30 made 230H.P. at 4600, and 285 lb.ft. of torque at 2800. It's hard to imagine that with a better intake, better cam, and better exhaust that you can't be pushing 275/280H.P. 50 horse from a cam, intake and headers? Is that reasonable? With the slightly more aggressive cam you have selected, maybe even a little more.
Re: What am I looking at for HP out of a vortec 305 tpi?
On my last 350 tpi build I used a set of SLP runners that had the divider wall cut way back and extrude hone ported. I got them from Shaneo, he had them for years.
I don't feel like spending the big $$ that aftermarket TPI runners command these days. I have a tig welder, what is the thoughts on taking the stock runners and turning them into 50% siamesed to gain some top end?
Re: What am I looking at for HP out of a vortec 305 tpi?
The 305 Vortec heads aren't the same "Vortec" as the 350 heads - from what I have read they are essentially L03 heads with a Vortec intake pattern.. And coupled with the cost of the SDPC manifold base, which leaves much to be desired in the flow department (TPI in general, without porting, can't keep pace with a 350 Vortec), makes them basically not worth the effort.
Just build a 350. You'll be much happier with the results. Heck those of us with built 350's are generally contemplating larger engines on our next build.
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by DynoDave43
My heads came off of a marine engine, actually. I missed out on the shortblock. Was that a TBI motor?
So again, in my case, a slightly warmer cam (but not by much), SLP headers, N10 and Borla catback...275 is not a crazy number? And maybe a little more for the OP, who has slightly more cam yet?
TBI, 4bbl carb and MPFI were all rated about the same. The Rochester 2bbl carb was rated around 230 hp.
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by GeneralDisorder
The 305 Vortec heads aren't the same "Vortec" as the 350 heads - from what I have read they are essentially L03 heads with a Vortec intake pattern.. And coupled with the cost of the SDPC manifold base, which leaves much to be desired in the flow department (TPI in general, without porting, can't keep pace with a 350 Vortec), makes them basically not worth the effort.
Just build a 350. You'll be much happier with the results. Heck those of us with built 350's are generally contemplating larger engines on our next build.
I had a set of 059s that outflowed a set of Hecho en Mexico 062s. The 059s flow in the mid 220 cfm range. The 062s did not hit 220 cfm.
The 062s were off a 350 crate engine that never made the power the OEM engine made that had 906s on it. The 906s flowed ~240 cfm.
Etec 170s woke that lazy crate engine right up. On a Vortec head comparison engine dyno shootout the Etecs made more than 40 hp more than the 062s. Cam was only a 222/230 @ 0.050 roller.
Re: What am I looking at for HP out of a vortec 305 tpi?
Wouldn't exactly call the truck intake lousy it outflows a factory TPI base in stock form and I am working on a ~500 hp 383 build running one. The truck intake has a very thick casting and a ton of room to grow port wise. I am over 300 cfm on my ported truck base and it was over 250 to start with. I was easily able to open up the truck intake enough to match the 210cc ports on my heads. Was not quite done with it in that picture but you get the idea. Stock truck base with no porting can support ~400 hp. The same cannot be said for TPI.
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by NoEmissions84TA
Curious what you plan to use for lifters?
If the factory rollers look good coming out, which I expect they will, I plan on re-using them.
Originally Posted by GeneralDisorder
The 305 Vortec heads aren't the same "Vortec" as the 350 heads - from what I have read they are essentially L03 heads with a Vortec intake pattern.
GD
No, the L30 head is not a downsized carbon copy of the L31 head. The combustion chamber is slightly different, and the intake port retains a SMALL ramp for swirl, somewhat like the L03 head, but not nearly the size or obstruction to flow.
As I said, there's not a lot of info out there on these heads. But there is a little if you dig.
The factory numbers:
Truck TBI 305 = 175H.P., 265 torque. Vortec 305 230H.P. and 285 torque. 55H.P. and 20lb. ft. gain.
Truck TBI 350 = 200H.P., 310 torque. Vortec 350 255H.P. and 330 torque. 55H.P. and 20lb. ft. gain.
So while the heads may not be identical, the overall package of cam, induction system, and heads seems to have been equally effective on both engines. Maybe even a tad more so on the 305 to produce the same power gain from less cubes.
I'm not saying they are world beating heads, but like everything 305, folks tend to write them off. And I think that's a mistake.
Originally Posted by Fast355
Wouldn't exactly call the truck intake lousy it outflows a factory TPI base in stock form and I am working on a ~500 hp 383 build running one. The truck intake has a very thick casting and a ton of room to grow port wise. I am over 300 cfm on my ported truck base and it was over 250 to start with.
Re: What am I looking at for HP out of a vortec 305 tpi?
Originally Posted by DynoDave43
If the factory rollers look good coming out, which I expect they will, I plan on re-using them.
No, the L30 head is not a downsized carbon copy of the L31 head. The combustion chamber is slightly different, and the intake port retains a SMALL ramp for swirl, somewhat like the L03 head, but not nearly the size or obstruction to flow.
As I said, there's not a lot of info out there on these heads. But there is a little if you dig.
The factory numbers:
Truck TBI 305 = 175H.P., 265 torque. Vortec 305 230H.P. and 285 torque. 55H.P. and 20lb. ft. gain.
Truck TBI 350 = 200H.P., 310 torque. Vortec 350 255H.P. and 330 torque. 55H.P. and 20lb. ft. gain.
So while the heads may not be identical, the overall package of cam, induction system, and heads seems to have been equally effective on both engines. Maybe even a tad more so on the 305 to produce the same power gain from less cubes.
I'm not saying they are world beating heads, but like everything 305, folks tend to write them off. And I think that's a mistake.
I stand corrected.
Agree on the 305 Vortec heads. My 99 Tahoe ran very well with a cammed L30 in it, full bolt ons and a looser S10 converter.
