TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I genuinely want to believe this, I really do, but I gotta be honest. This is a tough pill to swallow. You're coming very close to 100hp/liter. There are extremely few engines that have hit that naturally aspirated. The first two that come to mind is the Honda B16 in the civic Si, and many of the new K-series engines. These engines are dual overhead cam, variable valve timing techno wizzards. From oil cap to drain plug they are designed with efficiency in mind. You have a 2 valve small block chevy from 1955. You have eclipsed even the acclaimed LSx engines. I just can't get my mind wrapped around this yet.
The ONLY thing I can think of to explain this is that your intake may be hitting its perfect peak resonance at your peak torque and HP. This would have to be a result of perfect cam timing to interface with the resonant frequency of your intake components. This engine has the VE of DOHC performance engines, inertial supercharging is the only way I can think of to overcome the loses in the cylinder heads.
hey 86z im in ct also i used to have a supercharged tpi ,ran good but could never get it to run perfect because i couldnt get any1 who wanted to build a prom for a supercharged tpi. this was a few years back. i now have a 91 z an wanna go back to supercharge. my ? is do u know any local tuners / chip burners who would help out tuning it ,if u dont mind who tuned yours thanks.
30* plus the base, but the base is set at TDC or 0*. I run 22* in my timing table and 8* up top in the PE adder. With this table, wysiwyg.
Is the bin that you are working from a 350 bin?
The timing numbers are so low that they look like they are basically for an iron headed 350. A stock 305 bin shows WOT 30 deg + 6 deg in PE = 36 degs total.
I'm just wondering why you are using so little total advance on a highly modified engine.... I've always read that a cammed engine wants more timing than a stock one.
He's using Vortec heads, entirely different than what a stock SBC wants.
Timing is all relative, a cammed engine doesnt necessarily need more timing, depending on what heads and pistons are in there.
Exactly, the ideal timing depends entirely on the circumstances. Given how flat the torque curve is, he's got it pretty much perfect for his setup.
As for the numbers, eh. Even if they're a bit optimistic, he's still done a great job given the quality of the torque curve. He's clearly put a lot of time and effort into this tune.
hey 86z im in ct also i used to have a supercharged tpi ,ran good but could never get it to run perfect because i couldnt get any1 who wanted to build a prom for a supercharged tpi. this was a few years back. i now have a 91 z an wanna go back to supercharge. my ? is do u know any local tuners / chip burners who would help out tuning it ,if u dont mind who tuned yours thanks.
i do my own tuning, using code59 from code59.org, checkout our club
nec-f.org
I recently dyno'd my 305 TPI project that is currently in the 1983 G20 Van. After many builds, I have come to respect the little 305 and what it is capable of. When properly built they can turn out some HP. http://store.summitracing.com/partde...5&autoview=sku (Modified to my needs, ported and siamesed)
The heads were setup for .510" lift and the appropriate springs were setup for the camshaft specs.
I have been starting to collect parts for a 305 build that is very similar to yours. 305 roller block, KB 143 flat top pistons (+0.030), 059 vortec heads, ZZ4 cam, Vortec TPI intake with SLP runners. Also a set of Comp Cams 1418-16 1.6 roller tipped rockers.
If you don't mind a couple of questions... Can you tell me more about the changes you made to your SLP runners? How far down did you cut out the divider?
Much change to the Vortec intake base?
Did you go with screw in rocker arm studs? It would seem so with a strong spring and 6k RPM.
The vacuum to the crank case is interesting. Can you tell us some more about that?
I have been starting to collect parts for a 305 build that is very similar to yours. 305 roller block, KB 143 flat top pistons (+0.030), 059 vortec heads, ZZ4 cam, Vortec TPI intake with SLP runners. Also a set of Comp Cams 1418-16 1.6 roller tipped rockers.
If you don't mind a couple of questions... Can you tell me more about the changes you made to your SLP runners? How far down did you cut out the divider?
Much change to the Vortec intake base?
Did you go with screw in rocker arm studs? It would seem so with a strong spring and 6k RPM.
The vacuum to the crank case is interesting. Can you tell us some more about that?
Thanks, Scot
I would recomeend trying the SLP runners the way they come out of the box, then if you don't like them, then hack them up. My runners worked pretty well out of the box but fell over at higher rpms. I siamesed the exit of the plenum and the entrance of the runners. I left the divider intact near the base though, only siamising where the runners bolt to the plenum. I cleaned up and mildly ported everything and enlarged the gaskets.
The changes to the base weren't too drastic, just a cleanup and mild porting to match up with the heads and runners.
I DID use screw in studs on the heads. They are cheap insurance for what I am doing.
Vacuum to the crankcase is nothing new. Racers have been using vacuum pumps and converted smog pumps for some time now. I am using a belt drive emissions air pump reconfigured to pull air from the crankcase. It pulls about 7-9 in/hg on the crankcase which helps cut windage and allows the rings to seal better at higher rpms. Too much positive crankcase pressure is known to cause ring flutter which keeps them from sealing properly on the downward intake stroke and dilutes the intake charge.
I noticed for the rings listed that Summit says gapless second ring. Why not a gapless 1st ring? I bought KB's, and KB says to run a wide gap on the 1st ring. The gapless style seems like a better answer than a wide gap 1st ring.
Last years Engine Masters competition (EMc) had a 305 that dynoed approx 390 fwhp on an engine dyno. IIRC the owner used GM alum Fastburn heads (large port conventional-flow-cooling equivalents of the aluminum LT4 factory head) and a 236 deg cam IIRC, and the usual carb + headers.
Fast355's 305 engine: ported iron 059s with bigger valves will be a better burner of fuel than the Fastburn heads used in EMc, and they will flow just about as well..... and with the smaller port volume (170 cc vs 215 cc), the flow speed will be much better so the swirl and turbulence will be much better. So Fast355 will make better power with less need for spark advance. The port fuel injection will also allow much better tuning across the full range of rpms at WOT than the carbed EMc 305. So Fast355's assumed 418 fwhp (15% drivetrain loss via 356 rwhp) compares sensibly with the 305 build in the EM.
Finally, there is a long sticky thread in the TPI section here at TGO showing the comparison of approx 9 versions of TPI intakes and one non-TPI intake manifold, as used on a built 383. The worst TPI setup was the stocker (duh) and IIRC it made around 420 hp. So the stock TPI intake can move enough air to make 420+ fwhp using a big cam in a 383..... so it stands to reason that better flowing aftermkt TPI runners + Vortec lower base intake can move the same air while spinning at a higher rpm in a smaller engine (305), even with the small cam. You don't need a big cam to make big power if the intake & exh flow losses are small and the combustion (burn) is ideal.
I've heard the naysayers for years.....and while yes, it's hard to beat cubic inches, the more someone tells me I CAN'T do it, the more it makes me want to.
Now, mine is a carb'ed setup, but this makes me confident that I can reach respectable HP #'s with my mini-mouse.
After staring at the 305 head pictures for a while, I see that the area around the intake valve has been unshrounded. Did you bring this out to match the edge of the cylinder wall? Was it done freehand, or on a machine? It looks nicely done...
once again i wish i lived closer to you, just to get the inspiration, or tuning insight even haha!
it makes perfect sense to me that a more efficient, smaller engine can make more power than a heavier less efficient engine.
i think people get a little too carried away with going to big on heads. just because your heads flow a peak of 260cfm who cares..... how often are your valves open .600 flowing that?
the part that realy makes all the difference is the area under the curve which you clearly increased to its fullest.
there is no point in overcamming an engine because once again you are killing the area under the curve. I think what you posted is very plausible and the data is all here to prove it.
ps. you should move to ohio so you can tune mine lol . nice job again and thank your for all your insight.
How do you make a smog pump into a vacuum pumP?
id like to do that...
thank you
nice motor by the way i hope to be up there when mine is done...
I used a Ford pump from an 80s product that bolted right up to the brackets on my Van. The Ford pump pulled in air from the main engine air filter and not from behind the centrifical filter like GM pumps. The suction side is then connected to the crankcase and a vacuum relief valve installed in the opposite valve cover. I installed a breather filter over the relief valve to keep out dirt and other contaminants. The relief valves are typically adjustable and I adjusted mine to pull a peak of 7 in/hg vacuum. It pulled 7 in/hg by about 2,400 rpm and maintained it all the way up the rpm band.
Quote:
Originally Posted by flaming-ford
once again i wish i lived closer to you, just to get the inspiration, or tuning insight even haha!
it makes perfect sense to me that a more efficient, smaller engine can make more power than a heavier less efficient engine.
i think people get a little too carried away with going to big on heads. just because your heads flow a peak of 260cfm who cares..... how often are your valves open .600 flowing that?
the part that realy makes all the difference is the area under the curve which you clearly increased to its fullest.
there is no point in overcamming an engine because once again you are killing the area under the curve. I think what you posted is very plausible and the data is all here to prove it.
ps. you should move to ohio so you can tune mine lol . nice job again and thank your for all your insight.
Cylinder head selection will MAKE or BREAK your combination. Selecting and setting up the heads is even more important than selecting the cam. The cam has to match the heads, intake, exhaust, and short block. You also want to eek out ALL they dynamic compression ratio you can. It is also benifiical to get the exhaust out and keep the intake charge as un-contaminated as you can.
I have some pictures of the intake runners before modification and ported plenum I was running.
Finally, I stole this picture from another post from a member (cannot remember who) on here. Its a 083 350 TPI head with 1.94/1.50 valves on a stock bore 305. On a .030" over 305 there is even more clearance between the bore and intake valve. The 1.6" exhaust valve clears easily as well. I unshrouded the top of the bores as well as the cylinder head, both to more closely match the intake bores. The top of the cylinder bores typically have plenty of meat to withstand this, but I would do it before doing the rest of the machine work on the block in case by some bizarre circumstance you hit water.
I know I will get some grief here. This is the only picture I have of the 059 intake bowls. NO these heads are not swirl ports, they have a slight swirl vane in the bottem that is NOTHING like the TBI swirl ports. The intake ports are the same as the L31, down to the vane leading up to the valve guide, they just have the short swirl inducing ramp on the high velocity side of the port to help generate swirl. I still obtained 250 CFM @ .500" lift from these heads through a 1.94" intake valve and all the swirl you could need to get a good burn. Notice I had already machined on the chambers.
Here is a conventional non vortec port and a TBI swirl port for comparison purposes.
Fast355, as I often am in these discussions, I totally believe the numbers, more so, I’m surprised that we have some very experienced people here that seem to have a hard time believing them (that and I just got done reading the “Quest for a better flowing TPI” thread, which seems to lean the opposite way, reading most of their posts over there makes it sound like this should be totally impossible). Not that you really need it anyway, but unfortunately, I doubt that me agreeing with you helps at all, since I’m usually the one at your end, and even at the track have had monkey’s crawling all over the car trying to figure out “where’s the supercharger?” or “where did you hide the NOS...?”
That said, few comments/questions, comments first:
- Weird, numbers… well yea, try racing something the size of a bus, shaped like a brick that weighs 2000# more than an f-body… It’s almost exactly the same size, shape, gearing, drivetrain as my Blazer had, and my numbers had the same weird skew to them.
- I’m not sure why people expect such a big difference between a LS based engine and an SBC with nearly identical numbers… both are using a fast burn chamber, both have the same cooling and are very similar in design… the biggest difference is the 15* Vs 23* valves, and that’s more an airflow difference than anything else, and let’s face it, your combination is only making enough HP to use about 200cfm of airflow or so, so you’ve got more flow than you need. Honestly, I’m a bit surprised that you’re doing it with SLP runners rather than stockers.
- I like the torque and HP curves… they’re _exactly_ what would be predicted if you do the math on a TPI intake… your cam choice and it’s tighter LSA doesn’t interfere with the natural powerband of the TPI, which is basically fat in the middle and keeps going till you run out of air (your combination that should be somewhere ~6500 from what I can tell). As I keep saying, if you want monstrous fat low end, say in the 2000rpm range, than you really need something different than a TPI
Questions:
- How close are you on the detonation front? I’ve run combinations close to that before and always chickened out before pushing it quite that far, either a pulling back on the compression or finding a little more overlap to decrease dynamic compression a little for a little extra detonation control. I’ve always regretted it also, since I’ve never had detonation issues with anything I’ve tried like this, a few iron headed engines pushing or in the low 10:1 compression range which seem to run fine even on 87…
- What are those cylinder heads painted with?
-
Quote:
Originally Posted by Fast355
I do not have low-tension rings, but I do have an electric LT1 emissions air pump setup to draw about 7 in/hg on the crankcase @ WOT. It works as I saw 2-3 tenths of a second improvement in ET.
Quote:
Originally Posted by Fast355
Vacuum to the crankcase is nothing new. Racers have been using vacuum pumps and converted smog pumps for some time now. I am using a belt drive emissions air pump reconfigured to pull air from the crankcase. It pulls about 7-9 in/hg on the crankcase which helps cut windage and allows the rings to seal better at higher rpms. Too much positive crankcase pressure is known to cause ring flutter which keeps them from sealing properly on the downward intake stroke and dilutes the intake charge.
Huh??? The only thing I can figure is that you changed what you’re doing between responses?
Along those lines I have a smog pump off of an 80’s ford bronco that I modified for fittings that I’m planning on using the same way, I’m hoping that it is going to be close to a bolt in to the stock smog pump bracket, but I’m debating if I should try it or find another since the front bearing bore was a bit messed up and I had to use some JB weld to get a new bearing to seat correctly. What vacuum relief valve are you using?
- Do you actually have the valves unshrouded or are those just cuts from cutting the seats for the larger valves?
- Someone else already asked, but I didn’t see a response: what datalogger is that?
it makes perfect sense to me that a more efficient, smaller engine can make more power than a heavier less efficient engine....
More cubic inches will always have the final say in terms of power, but I definitely agree, people make a huge mistake by trying to build their 305's based around the more common 350 selection of parts. Fuel efficiency, valve train symmetry, and air velocity are the real keys. Smokey Yunick knew this very well, and made enormous power, with similar bore sizes to that of the 305....
I’m not sure why people expect such a big difference between a LS based engine and an SBC with nearly identical numbers… both are using a fast burn chamber, both have the same cooling and are very similar in design… the biggest difference is the 15* Vs 23* valves, and that’s more an airflow difference than anything else.
The LSx is too highly regarded for the few additional benifits it gives. While it is a tough, capable engine, its older brother the SBC CAN and WILL give it a highly competetive run. The GenIII motors were designed to do one thing and one thing only, meet the ever tightening smog and CAFE standards as cheaply as possible.
Quote:
Originally Posted by 83 Crossfire TA
Let’s face it, your combination is only making enough HP to use about 200cfm of airflow or so, so you’ve got more flow than you need. Honestly, I’m a bit surprised that you’re doing it with SLP runners rather than stockers. I like the torque and HP curves… they’re _exactly_ what would be predicted if you do the math on a TPI intake… your cam choice and it’s tighter LSA doesn’t interfere with the natural powerband of the TPI, which is basically fat in the middle and keeps going till you run out of air (your combination that should be somewhere ~6500 from what I can tell). As I keep saying, if you want monstrous fat low end, say in the 2000rpm range, than you really need something different than a TPI.
I ran the engine with stock runners and it fell over really hard around 5,500 rpm.
Quote:
Originally Posted by 83 Crossfire TA
Questions:
-How close are you on the detonation front? I’ve run combinations close to that before and always chickened out before pushing it quite that far, either a pulling back on the compression or finding a little more overlap to decrease dynamic compression a little for a little extra detonation control. I’ve always regretted it also, since I’ve never had detonation issues with anything I’ve tried like this, a few iron headed engines pushing or in the low 10:1 compression range which seem to run fine even on 87…
- What are those cylinder heads painted with?
.
My heads are not painted with anything. The one in the picture looking into the bore was actually another TGO members that I used to show 1.94/1.50 valves on a 305 bore to debug the myth the valves are heavily shrouded.
I ran the combination on 87 octane with a mild timing advance curve and ran a hotter curve on 93 octane. I even left the hotter advance curve in the chip and ran it on 87 a few times. The 7730 has a low-octane spark advance logic that retards the open throttle timing map under moderate-high loading and rpm if the knock sensor is picking up detonation. I saw the low-octane mode retard flag showing on some datalogs and just ran good gas in it. I also ran this combination on 104 octane E85 and it ran GREAT on it.
Quote:
Originally Posted by 83 Crossfire TA
Huh??? The only thing I can figure is that you changed what you’re doing between responses?
Along those lines I have a smog pump off of an 80’s ford bronco that I modified for fittings that I’m planning on using the same way, I’m hoping that it is going to be close to a bolt in to the stock smog pump bracket, but I’m debating if I should try it or find another since the front bearing bore was a bit messed up and I had to use some JB weld to get a new bearing to seat correctly. What vacuum relief valve are you using?
- Do you actually have the valves unshrouded or are those just cuts from cutting the seats for the larger valves?
- Someone else already asked, but I didn’t see a response: what datalogger is that?
I DID change the vacuum pump between posts. The LT1 electric pump burned up after constant use, it was a stock 1995 or so GM piece and it just didn't last long. The belt-driven pump seems more reliable and it is even in use on the current engine.
I found the vacuum relief valve on Summit/Jegs but cannot remember the part-number, they market it as an adjustable vacuum relief valve
The cutter did cut into the chamber, but I performed some hand unshrouding as well. I did the top of the bores as well.
i just want to say this is one of the coolest engine builds i have seen and it has motivated me to try my own 305 TPI build. I like this idea of it because thats what engines came in these cars and its kind of cool to make power with what you have. How long did it take you to do the tuning? and how did you accomplish it? Did you use a wideband and just street tune it or did you do it on the dyno?
Man screw all these naysayers....you built a damn strong 305 and more power to you! I have similiar plans for my 87 z-28 305 retrofitted with a '7727 ECU and EBL flash system for tuning (I use tunerpro software and am just getting my feet wet with tuning...been a carb guy all my life...I'm currently enrolled at wyotech and am starting High Performance Powertrain here in a few weeks..she is gonna be my project in class) and your post helped me out tremendously...I appreciate everything you have posted and will be referencing it for my own build...356rwhp is outstanding man....hopefully I will be able to build a comparable motor now that I have some base specs to work with...thanks again!
Last edited by 3rdGenFreak1227; 06-08-2009 at 01:20 AM.
Reason: added info
what exactly did you have done to ther heads? did you port them or did you take them to a machine shop? and just a figure of about how much did it cost for the heads to be ported and such if you didnt do it yourself?
FYI, Scummit update their website so now allot of links in your original post are now bad.
Great thread!!!
__________________ www.TheFOAT.com/92GTA 1992 Trans Am GTA SLP: GMPP optioned "SLP Performance Parts Package" GTA, 210K Miles, Dark Jade Gray Metallic, LB9, 4L60, T-Tops, and Gray Leather. Documentation includes Window Sticker, Factory Invoice, Etc. Added a few tasteful mods. Owned for 10 years since 69K miles. 2nd place trophies. - Currently undergoing restoration to brand new condition with as many NOS parts as I could find!!! -
this is a great thread indeed! congratz on those numbers, i know i'm a little late but i just found this thread this is most probably the most efficient 305 (N/A) build on this site!?
anyways, since summit updated their website structure, i re-did the links that stopped working for me here:
. nice job again and thank your for all your insight. 
this is most probably the most efficient 305 (N/A) build on this site!?
