TUNE PORT TECH-L98 vs CARB 

Had an 89 L98 Corvette....insane throttle response.

Low RPM torque feels better in a street car. Making power at a higher RPM can actually make a car feel slower in most street use. More low RPM torque also gives better fuel milage. I love the TPI. Best looking production intake manifold out there IMO and I like seeing the solutions people have come up with to make power with it.

13 dislikes? Must be Ls swap guys....Great video Richard.

Those ole L98's were tire stredders... they were fun from red light to red light

Thank you for doing L 98 engine

Years ago I did a TPI 350 swap into a 79 Firebird with a 3.42 rear and a TH350 trans with a 2500 stall converter. It wasn’t fast, but it was a lot of fun on the street, and that car was a ridiculous burnout machine!

Just imagine how the minds would had been blown if gm would have dropped the tuned port 350 in there pickup trucks I've always said that it would have been the best pickup engine gm ever produced

Love the tq of the tpi. Especially from a cruiser.

I agree the tuned port injection combined with the Vortec heads would have been a great truck engine.

TPI is great for the street. Low end torque allows you to run a higher gear.

The truck use comment is seriously an identical comment my buddy made about a year ago. He loved TPI Camaros and still believes in a truck they would have rocked!

This video really makes me change my mind on building my 85 vette.

I’d like to see an L98 build strictly for low end torque regardless of the top end power I’ll bet you could get nearly 550 foot pounds from a stroker tuned port build.

I'm a guy who builds for efficiency an low end to midrange torque for daily drivers. Most of what I build peaks the power band around 5000-5500 rpm. I've seen gains of double horsepower and torque from the late '70s carbed applications, with 30% mileage gains, depending upon application. Takes the right combo to do it... I was kinda surprised that carburetion vs efi alone was better for ultimate power. I always liked the feel of a carburetor over efi, but never tested them like Richard has. But then again, I spent many of my years debunking basic engine designs and "wisdom" from machine shops when they effed up my build..... nothing is more disheartening than to drop $5k on a nice efficient build, and have the machinist say it runs better than ever, and have it bog out in the low end. A friend had the same experience with a 383 K10, and bought a '79 f350 4x4 with a stock 400 that walked all over his "built" 383... It's pretty cool to see what works on the dyno, and what parts make what changes. I would like to see, though, more dyno graphs around the 1500 rpm and up ranges, where daily driving efficiency takes place!

Great post - Personally, as a 63 yr old cruising guy, I like the stock set up for the type of driving I do (`88 C4 L98 auto - no frisbee) For street driving I can jump out of the hole and hang with a lot of other rigs out there. Great post.

I love the tuned port intake for a street car. Wicked torque under street driving conditions and looks wicked good to boot

I enjoyed my L98 Corvette, had a auto with 3.08 gears, torque was amazing, but my 93 with a LT1 6 speed was the best

Excellent demo of the runner length calling the play...an l98 tpi motor in a truck would have been awesome for sure. For a heavy street car, drive in, foot brake et bracket car. I would go for the low end, the right cam, with a converter that would flash high, launch good make the converter do the work, when dialed in should be a very consistent combination that should last a long time...this is a street/strip foot brake et car...drive in drive out...not a 10:90- 9:90 bracket monster. With a od lockup trans, great mileage driving to the track too. My 75 Monza, would like this...hmmmmm!

Imagine the odd feeling one gets when theres a sense of relief that it's a SBC test rather than an LS test

Always built low compression motors for the street ( max 9:1 or so). Built them for low and mid-range torque. Horsepower was nice but Low/ mid range torque busts the but best. In my day usually ran dual plane intakes with either two barrel Holley or small Holley four barrel. If I built one today I would definitely go with a Fitech or Holley throttle body fuel injection. I always kept lift on my cams at or below 0.550 with duration around 220-235 degrees. Lisa at or around 112 degrees. No experience with the tuned port but was pleased to see its torque production down low. Thanks for your tests. I really enjoy them. Your a great educator!

Thanks again for a awesome comparison 👏

Low end Torque is always the way to go for the street !

I loved the look and potential of the TPI system that I converted my 92 RS 305 from TBI to this. That was all the way back in 2000.

I also remember people throwing in high lift cams in these engines back then. I guess that wasn’t the best way to go with the Long port runner. Needed these videos 20 years ago! :)

Richard, my son and I used a Comp 08-302-8 on a 355 Tpi. Stock cast iron l98 heads were reworked with a valve job and new ls6 blue beehive springs and roller rockers. Topped it off with long tube headers and 4 th gen Camaro cat back. It sounds good and pulls hard. This engine was from a GTA and replaced the stock 305 tpi. My son is very happy with the combination of this tpi engine and the t56 transmission. 3.91 gears are coming next!

Amazing demonstration of runner length. Very informative! The best channel ever!

Awesome information. The old Ramchargers Drag Team had some really interesting home brewed intake manifold designs back in the early 60's on the Dodge and Plymouth stuff. They did a ton of experiments with intake runner length. Thanks for the continued education. I learn something new every single time I watch your stuff. I really look forward to it. Thanks. Dig the shirt too, by the way. Great kids come from great parents.

Would really like to see a vortec test with the stock intake

This video answered several of my questions regarding tuned port vs dual plane. Thanks. Putting that video of dyno tests on several tuned port systems sound great! BTW that mild cam caught my attention. I had a 208/208@.050" with 108 LCA and dual plane manifold with long tube headers and super free exaust 40 years ago. It shocked a lot of people. I cut the transmission cross member into 7 pieces and rewelded it so the exaust humps were lined up with the collectors. I also had to rest the weight on the cross member, remove the seats and beat the floorboards with a 5lb maul to ceate a clearance for the cross member. I always wondered what a tuned port injection would do on that set up.

Built a 350 to put the tpi on with tons of research, Cam, compression, Injector size, gearing, power ranges rpm and this one video was a pretty good summary of most of it.

Very well done. It was always hard to convince the pups that it's all about where you want to run your RPM range on a consistent basis. The TPI was designed to get optimum performance AND mileage! Can't do that with the carb. It's one or the other! (You couldn't make power AND meed EPA CAFE standards) Straight from the GM engineer in Detroit back in 86', (GM Training School) the 700R4 transmission was made to overcome the mileage loss due to the lower rear end ratios that were used to make you think the engines actually had power! You hit the nail on the head with the runners and the low end torque. It was part of that equation. Once you run out of HP (RPM), upshift and catch the torque band again! I once found a web page (20 years ago) that had the Chrysler data on their Cross Ram experiments showing where the torque/HP band was for a given runner length. Haven't been able to find it since! It was fascinating. I wish I would have printed it!

I just "finished" my small block 383 i am using a port matched blended holley stealth ram air system with the commander950 management with stock c4 corvette manifolds and made 358 wheel hp. Made 373 lb ft , on a mustang dyno, with one of the flattest torque curves that i have ever seen. Now i need to make a set of 1 5/8 long tube headers and make over 400 whp!

TPI on a 383 with a mild cam = torque monster. Seems like it'd be an awesome setup in a pickup or suv

When I see this stuff it always reminds me of the thought of what GM was thinking with the trucks... Here's a truck engine that would have blown the TBI junk out of the water for torque.... and does. They could have even run the swirl port heads with it lol. Even better... release the Vortec head in 1996 and then literally put the worst intake and fuel injection system they ever created on top of it. Would have been better off doing a sequential setup with TPI until the release of the LS.

Great Video! Love it! We can argue all day about the merits of both, but the looks and quirky cool factor of the TPI cannot be denied. I'm doing a buildup of my low mileage of my 87 Corvette. For me, there is no choice. The TPI system (mine is ported), along with the "Atari" dashboard IS the identity of the C4 Vette.

Congratulations on over 70 thousand subscribers Richard. 👍

I had a FIRST fuel injection system about 10 years ago. I wish I still had the dyno test from it. Mild camed 350 w/ 389hp & 413 torque. I'd like to say that toque started to really pick up at 2300 rpm and maxed out at 4800. I had to sell it becuase of life before I was able to install it. Would of been an awesome dd /cruiser. I would love to see the tpi test you did in the past.

Richard looks a lot calmer than usual, it caught me off guard for the first minute 😂

Haha ... I'm wearing the same shirt right now as what you had in the video :o) Daughters are awesome (at least that's who gave me mine!) You showed me some great information here. I've put together an L98 which is on the cusp of first fire up. What's kewl about your video for me is I was able to pick up a Holley Stealth Ram for it, with the 58mm TB. The cam in it is a Comp Cams 08-305-8 (.544"/.554" lift, 220/229 duration, 114LSA on 1.6:1 roller rockers). I have a set of aftermarket aluminum heads which flow 250cfm @ .550" lift. I'm shooting for 400WHP and I think the numbers you've shown with stock heads and a bit of a milder cam than what I have should put me in that ball park. I'm really looking forward to getting this thing fired and on the road.

Richard you should do a test the TPI on all the Gen1 small blocks 283 to the 400..... Awesome video

Your combination of energy, know how and curiosity is amazing! The amount of theory and combinations dyno tested by you generates a wealth of information! I can’t help but wonder how a TBI set up and an Accel super ram intake would perform on this exact L98. Thank you for all the hard work in the dyno room.

I like the TPI for the street and have 2 vettes with them. One is a large tube lingenfelter engine and the other is stock. As you indicated the modified engine just amplifies the stock power curve. The LPE engine is around 400 CHP and still gets 30 MPG. My carb'd 350 is lucky to get a 1/3'd of that. So on the street the TPI is such fun with excellent response and it indeed feels like a bigblock. I take mine to the drag strip from time to time and it usually leaves me disappointed since the RPM range shifts much higher than the street. The cars low end torque makes it hard to launch with street tires and the 60' times are critical in a RPM limited car.

You read my mind Richard, a TPI style manifold on the Vortec 350 would’ve been fantastic, I’d also like to see an original TPI system on a 327, I feel like the smaller displacement would allow it to rev a little higher and maybe carry the torque curve a little higher in the rpm range.

This is Awesome! Some Classic TPI love

I sooo look forward to these videos everyday 😁

I find it funny that if anyone even mentions the L98 aluminum heads on a forum the immediate response is "Buy some AFR's or TFS heads". When you're 16 years old, it's 1993 so aftermarket heads are not near as prevalent or cheap, and an older student working at a junkyard says they can score you a set of 113's for $500.... You jump on them. After a little port cleanup and on top of a 10.5:1 327 with a healthy cam, those heads will support more than enough power for any 17 year old to be driving around on the street in a lightweight '69 Nova. My HS autoshop teacher pulled some strings to get the engine on a friends dyno. It put down similar numbers to the carbed L98 you tested(360 something) and the car ran mid 12's at E-town.

Looking forward to getting my 1966 El Camino TPI 357 in for a dyno test 😊

Great video..! My neighbor has the long tube TPI in his old 78 silverado with th350 trans and 33" tires.. The power comes on like a light switch, but does not like to rev at all.. (maybe 4200 rpm and feels asthmatic - a lot like the 6.2L non turbo chevy diesel)...

I love the way you talk in this intro! i can't stand the stop and go way you do it in your other vids, this way is sooooo much better! Keep it up please!

Always liked the look of the Holley Stealth Ram intake.

Good test. I have a similar build I'm working on right now. Except the L98 heads I have, are flowing up there with stock cathedral port heads. Can't wait to see what it comes out to.

I just got my old IROC that I drove in the 90's back on the road. Loving the TPI torque, but could be a little faster. Keep the TPI vids coming. I like the idea of an optimized long runner setup, maybe with a little cam and some vortec heads. These parts are getting harder to find and expensive.

Maybe modern carbs are better at this now, but in the '80s it was wonderful to just walk out to the car whether it was 0 deg or 100 deg outside and just turn the key and have the engine start, first time, every time. Plus that low end torque never fails to put a grin on your face.

Agree 100% on your truck comment. I had a 1992 C1500 5.7 5 speed, 3:73 posi SCSB. I swapped an L31 Vortec crate motor from Scoggin Dickey, Edelbrocks MPFI vortec intake system. GM is always stingy on trucks and messed up for decades. The crappy TBI then the spider intakes on Vortec trucks.

Depends on the day maybe, once on HRPT my small block in a 72 mailbu was accused of BBC after a couple rolling start races on the interstate, that day I was very pleased to have all I could on top. Thinking back on those wins just makes a guy smile.

Absolutely love all these videos and real world motor scenarios, and keep the “OTHER GUYS” videos coming

Never stop with Star Trek references!

That is what makes the variable geometry intakes Ferrari uses so cool. Pulling out all the stops is also why there 6.5L can make 789 net HP on 89 pump and still be clean enough to legally sell. That's impressive power from only 396ci all motor being a V12 just makes its sexier.

Since boneyards are full of TPI setups that no one wants combined with the availability of aftermarket ECUs and the SBC still being the cheapest to build, this makes me want to build a TPI setup for my tow pig and replace the vortec TBI.

I prefer the TPI intake manifold for my trot line weights.

I knew a guy that did a 350 TPI swap on a GMC Sonoma. That little bucket was sooo crazy 🤙🏾😂.

Thank you for your unbiased well informed experiments. TPI all day for daily driving. Less rpm less spring pressures and lower rpm for less possible ware and tare. It’s hard to pick one. Maybe average numbers would give a better idea. Also I believe a lot of guys have the shifting points incorrect for the tpi. Hurts quarter times extremely. For instance my tpi 350 tries to shift upwards of 4800 rpm which I think 4.3-4.4k is probably more in the max power range. .

Gee, thanks mate, very interesting, the thing is this,,, i have never been a fan of rev the crap out of something, WHEN, you can get serious grunt at a lower RPM, my 89 vette is SUPPOSED, to be 240 hp 340 t at low RPM, i dont know if anything has been changed Int, but it has A/M runners and from the runs i have had on the street, it goes way better than those figures.... So to keep the grunt where it is,,,, a PUMP AT 25 PSI, is what its getting.. thanks again for TPI stuff. Eddie Sydney Australia.

I used to have the factory TPI intake on a 400 in my '94 Silverado. Good power but ran out of air flow too soon. Switched to the Stealth Ram and love it. I still have the TPI intake and plan to use it on a 302 or 327 for an S-10. Should be awesome for the smaller inch engines

You brought up so many great points especially why GM didn't use the TPI engines on their trucks with the vortec cylinder heads. Can you please do a video comparing the l98 with the LT1?? That would be a great comparison.

I'm running TPI so i made the choice. The plan was to add a turbo but that would only worsen traction issues. Went there after running a small displacement with rump rump cam. The torque is much more fun.

Around 1989 Ford offered all kinds of support for the 5.0 pushrod Mustangs. Cams, heads,headers, rpm extenders, "off-road" catless h-pipes, everything. GM offered zero support, unless you were scca firestone/firehawk road racers. It was a curious time for sbc 3rd gen cars. A bunch of high$ companies selling junk that barely made gains. Throwing away the tpi for a carbed rpm airgap would have made good sense

Another great set of tests.

I'd put a Centrifugal supercharger in the motor with a TPI manifold. Low down torque for street driving, rising boost curve with RPM to get top end power

Richard I watch your videos from beginning to end these are some of the most informative videos I've seen yet.. I can't wait to watch when you break down and analyze the LT1 and LT4 engines...if possible please let us know your factual opinion on the torque-head ignition control system vs the optispark system

Richard Holdener Dude I absolutely LOVE that shirt!!!!! I actually have the Othala rune on my arm for ODIN. SKAL BROTHER!!!!!

I personally think the TPI intake is the coolest looking intake setup ever. I've been very tempted to swap to a TPI setup in my 67 Camaro just to have something different than all the big blocks or LS swaps I always see.

If it was me I’d take the perks of EFIs reliability and drive ability along with the extra torque. If I was going to build a race car, it would be a different story. But I drive my stuff to work and to the store, bangin through the gears on occasion

I agree with you Richard. It would of been amazing if they put a tuned port manifold on a truck. Like the early 90's ss 454.

Carburetor and manifold been around for a long time look how successful they are at the racetracks

ive got an l98 with the proflo 4 carb efi and i love it

for some reason i saw fat thor, took me by surprise. love the shirt. going to watch the rest of the video now.

I would definitely go with the dual plane intake but go with a self learn EFI setup !!!! And no stealth ram!!! Looks cool and was cool if you had one in the 90’s on your vette or Iroc!!!!

In my zf6 vette a have a crane compucam an a lingenfelter manifold , was looking for higher rpm horsepower ,that worked well👍

Kegaladon! Best intake ever!! You better get a patent on it! It is going to look awesome sticking out the hood of My S10!!

Hey Richard, love the channel. Just wondering 6 there will be a test in the future testing e85 vs water/meth showing timing numbers with each?

Power down low= Red light racer👍

Being a product of the 80's and 90's, I have a natural affinity for the TPI setups. I have owned a a 1985 Corvette and a 91 Camaro Z28 5.7, both obviously with TPI. Always loved the that low end power, and they would light the tires up with a blip of the throttle at a stop light. I would love to get back into a C4 or 3rd Gen F-body with TPI. I know any new muscle and even today's V6 Camery's and Accords would probably be as quick if not beat a stock TPI car, but just to have that feel- that low end instant grunt. Since I don't race every person I see or at a stop light (anymore, grew up from that :) ), I don't need the high winding power. I would pick TPI. There doesn't however seem to be any support for them anymore and with good reason, I know that LS tech has gone a long way. Still, a properly cammed TPI would feel soooo good as a daily driver.

This may not be popular but I'd like to see some kind of GM TBI build. Just to see what can be done. Turbo? Cam? Heads? Just curious.

This channel is excellent at disproving all the stories with facts! I am in the medical field, and we do many studies, your methods are comparable to our methodology. Everything is proven by Dyno results. Please do the stock intake vs. “cold air intake” and prove these don’t work! Biggest ripoff in motor sports.

Hello Richard.... great content... I remember the L98 TPI... my very first fuel injection car... 85 Corvette’s came standard with the L98. Even though it was Rated at 245 hp and 340 foot pounds of torque...... the L98 felt like a beast with that intake manifold form Idle to around 4000 RPMs. The dyno shows a disappointing top end power output.....but on the street the L98 with the right gears feels like a more powerful engine then what the dyno graph shows.

In the first test, there wasn't much loss of torque, but the gain of horsepower was generous. I'd opt for the carb setup due to the cheap gains.

tempted to put a variable runner length intake manifold on my daily driver to improve the overall powerband. that and some variable valve timing would be nice.

At points in time I had GTA and IROC both with TPI ..... loved those engines .... great torque and long legs

Richard, I know you’re the guru of intake manifolds and I would absolutely love to see a shootout between the venerable 67-69 Z28 vs the L79 and a slew of aftermarket SBC intakes. Maybe you’ve done this already and you can link the test? Great work as usual

I would pick the L98 injection for my usage case because anything I build would be just a street driver or daily. So i'd benefit from the easy cold starts, throttle response, more precise instrumentation and on the fly fuel trim adjustments. Unless i'm really ringing the car/truck out on the street for some reason it won't really see much time above 5000rpm. If I were building a track car that spends most time high in the rev range then of course the carb wins.

Cool. Got an l98 vette I'm gonna carb as soon as I can

Just found out last night that I have cast iron L98 heads on a engine I'm putting in my project muscle truck. I was wondering what kind of HP it would make with a cam and BAM! , you put up a video of one 😂 I plan to do a little port work to mine though and a turbo with blow thru carb eventually. Have you ever dyno'd some ported L98s?

How about 1996 - 2000 Vortec fuel injection vs carb?

Cool stuff! Definitely one of the greatest channels I have watched involving my favorite engines. The Chevy 350 Gen 1& 2 rollers. My other favorite is the Chevy 305. Why? Get this....It's actually because of the way the Box Chevy Caprice 305's would idle so soft and quietly. My late Grandfather had a 1982 that would blow cold A/C and was so quiet you didn't even know the car was idling! Why I love the Chevy 350 is a no brainer....This is probably one of the only motors that I know off that will give Hot Rodders and Muscle Car Guys something to due on the weekends when there is nothing to do, because you can always add to it or try new stuff or combinations out. 2 thumbs up !!!

I would love to see you explore taking the “factory TPI” up a notch to a “sleeper factory looking engine”. I, like you, love the look of the factory TPI fuel injection and will keep it on my 89 Corvette that I’ve owned for 20+ years. However, I would still like to maximize the factory set up!

Great video!

The TPI on a 350 truck motor and slightly higher compression ratio. And 1.6 roller rocker. Does in fact have more torque down low. The only thing left is an RV roller cam. Later when is time for my truck to be rebuilt. I will install an RV cam.

I have a 1987 corvette, I can’t speak for the other engine but I love my L98. It has fun responsiveness and heavy torque that makes the ride enjoyable. The power is manageable and not over the top either.

Hey Richard, what about the early 80's Crossfire intake, did you ever test one of those?