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.
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Originally Posted by MatthewMiller
I guess one man's overpowered is another man's just barely enough power. My car pulls hard to about 6000rpm. It's plenty usable below 70mph, especially with autocross rubber on it. It's nowhere near the peaky, high-rpm-only VTEC motor that many TPI advocates would have you believe.
By your description above, I think you missed my point. I'm SURE your setup is "useable". I figured your question is whether MY torque is "useable". If I ran drags on the street, it would be stupid fast from light to light. My point was where it consistently GRIPS in upper 2nd and 3rd gear. For me, that works out just right on street tires.
If I got a set of Goodyears (vs Sumis), it would be even better.
Where I'm sure an HSR conversion would help is in the acceleration rate THROUGHOUT 3rd gear. (4th gets into 100mph range and doesn't matter for the street).
Matt...you think in terms of autocross where the course (and tires) would dictate the best combo. FWIW, my HSR was sold...then purchased back. In 2010, I SOLD to an auto-crosser who mounted it IN PLACE OF A LARGE TUBE TPI...then went back to the TPI for the classes he raced in. (At least that's what he said). I think there were too many turns AND it pulled better with the TPI out of them.
My heads/cam are better though. I've got more lift and similar overlap (112 LSA). I probably SHOULD have picked the 108 YOU have for a TPI. (Because it lowers the "hump"). But, I picked a cam that I thought would work equally well in an HSR or even a FIRST intake. (I sold the HSR AFTER building my combo....then bought it back. It's TOO CLOSE A PERFECT port match to my AFR heads NOT to try it some day.)
If you've seen a dyno for the FIRST, larger tubes do move the resonance wave higher. It performs pretty close to a superram. It has 200-300rpms lower peak but with more torque. Again...for me...the torque bump of the FIRST would be worth it.
Application is the issue. Race or Street or Race or Street?
Or...Auto-X!!!
Last edited by GREGGPENN; Nov 16, 2017 at 12:00 AM.
When stock TPIs are converted to LARGE tube setups, then tend to gain .1 (or about 10hp). If you converted an LTx intake, you'd trap the 1/4m slower. HOWEVER, the TPI shootout shows you the potential "under the curve" gain for the TPI bubble might get you 20 on a 350. We've already covered it's gonna be in the 2k-4k range...and probably narrower. To be conservative, 2500-3500rpms.
I am not concerned with possible 1/4 mile projections, this is a street car and the performance is going to be FAR FROM STELLAR! If I wanted a car with high performance to brag about it's horsepower, I would buy a new production car but like I stated in other threads I love the style of my F-body and I am happy with my LT1 motor, but I desire to alter where it makes it's power.
Originally Posted by GREGGPENN
So...WE are saying you can get MORE gains in a wider power band with heads OR a stroker....versus an intake. When you add in the headache of installation AND if you need to modify a TPI at all...It just makes zero sense. Any and every builder knows that and has TOLD you that. Making us repeat it and explain why IS being a pest.
I am not committed to the TPI intake conversion just yet; I am evaluating whether or not I can achieve the performance I seek using my stock LT1 intake and the necessary components such as port velocity emphasized DART heads in street configuration, and the necessary custom grind camshaft.
Originally Posted by GREGGPENN
We've told you things that a common sense for our combined shared experience. Yeah...You WOULD lose top-end with the L31 cam suggested....But you'd lose it in rpms where you SAID you WANT to lose rpms. Now you've changed your tune A-GAIN.
Here is the problem I notice:
The L31 camshaft cuts out too soon and with LESS torque production while the TPI extends that peak much further.
What I am looking for is a torque curve from my stock LT1 that replicates a TPI L98 with a ZZ4 camshaft
So, how do I achieve the results in the third and last torque curve graph with my LT1 and stock intake? I am thinking I need to use a TPI intake and either have a custom grind made that replicates the ZZ4 or just use a ZZ4 camshaft in my LT1 with the DART Pro 1 180cc heads, custom long tube headers, and necessary dynotune.
As much as the stroker option will give me what I seek, I am concerned about that city driving mileage loss. I want to remain around 15 mpg in stop-and-go traffic, while I stand to gain in highway mileage I will lose in city mileage and city mileage is what I encounter the most! This is why I am seeking a non-stroker build and why I am targeting the TPI intake.
Last edited by Phoenix'97; Nov 16, 2017 at 06:26 AM.
By your description above, I think you missed my point. I'm SURE your setup is "useable". I figured your question is whether MY torque is "useable". If I ran drags on the street, it would be stupid fast from light to light. My point was where it consistently GRIPS in upper 2nd and 3rd gear. For me, that works out just right on street tires.
From light to light in either your car or mine is most likely traction limited. It is in my car, anyway, with tires that have grip along the lines of Sumitomos. First gear is silly at any rpm, and second will blow the tires away most of the time, too.
Where I'm sure an HSR conversion would help is in the acceleration rate THROUGHOUT 3rd gear. (4th gets into 100mph range and doesn't matter for the street).
Do you have stock gearing? I do, and my car at stock redline (6400rpm) is good for 109mph in third gear.
Matt...you think in terms of autocross where the course (and tires) would dictate the best combo. FWIW, my HSR was sold...then purchased back. In 2010, I SOLD to an auto-crosser who mounted it IN PLACE OF A LARGE TUBE TPI...then went back to the TPI for the classes he raced in. (At least that's what he said). I think there were too many turns AND it pulled better with the TPI out of them.
Autocross runs are almost always done in second gear, with no shifting. As such, they tend to emphasize flexible engine performance with wide power bands. Again, even with BFG Rival S tires, I usually can't use WOT coming out of corners in second gear. If I had a TPI intake, it would just be harder to manage traction at low rpms. OTOH, the ability to pull hard to near redline is helpful for the faster parts of courses. I spent years racing at TPI-equipped 92 Camaro in a stock class. If I had ever moved to a class that allowed different intakes, a short-runner intake is the first mod I would have done! And in my experience, whatever is good for autocross runs is also good for street driving: the most flexible engine possible, that requires the least shifting to get good performance.
What I am looking for is a torque curve from my stock LT1 that replicates a TPI L98 with a ZZ4 camshaft Attachment 48225966
[B]So, how do I achieve the results in the third and last torque curve graph with my LT1 and stock intake?
So re the curve you posted from the L31 cam, do you know that that's from an otherwise stock L98 with nothing but a cam swap? Because I think you're comparing oranges to apples.
Also, I'm calling bullshit right now on the posted curves for the L98 with ZZ4 cam. No otherwise stock L98 (stock everything, including exhaust) with just a ZZ4 cam is going to pick up 78hp (assume about 225rwhp for a stock L98) and have a torque curve that's flat to almost 5000rpm, and barely tapers off for the next 750rpm. I mean, just look at the TPI graph in the C-P-C chart you posted just above that: it drops like a rock after about 3200rpm. I don't think that graph is from an all-stock L98 with only a ZZ4 cam swap. It might be an L98 with a Miniram or other short-runner intake, or various other mods, but it isn't all stock. Where did that chart come from?
Actually, if you look at the LT1 torque curve in the same C-P-C chart, it looks almost exactly like the ZZ4 graph you posted! That is, the stock LT1 torque curve is by far the closest to the ZZ4 curve you say you want to emulate. What you are actually asking for here is a torque curve typical of short-runner LT1 intakes and cams!
Last edited by MatthewMiller; Nov 16, 2017 at 02:07 PM.
Also, I'm calling bullshit right now on the posted curves for the L98 with ZZ4 cam. No otherwise stock L98 (stock everything, including exhaust) with just a ZZ4 cam is going to pick up 78hp (assume about 225rwhp for a stock L98) and have a torque curve that's flat to almost 5000rpm, and barely tapers off for the next 750rpm. I mean, just look at the TPI graph in the C-P-C chart you posted just above that: it drops like a rock after about 3200rpm. I don't think that graph is from an all-stock L98 with only a ZZ4 cam swap. It might be an L98 with a Miniram or other short-runner intake, or various other mods, but it isn't all stock. Where did that chart come from?
I don't think that graph is from an all-stock L98 with only a ZZ4 cam swap. It might be an L98 with a Miniram or other short-runner intake, or various other mods, but it isn't all stock. Where did that chart come from?
You are right, but this graph gives me an idea of what I could expect with a ZZ4, OR Lloyd Elliot custom grind version, using my stock intake and complimentary bolt on parts.
I am researching all of this but I realize that if I do decide to put a TPI intake on my car, I need to figure out how to balance it's torque production on the low end with being encouraged to expand that torque curve by shortening the runners and totally porting out the intake for more airflow. At that point I would be better off keeping my LT1 intake while I think about it.
I am not going to get all involved in this discussion but a ZZ4 cam would help you with torque down low. To do what you want which is maximize low end power you need to get cylinder filling at low RPM to do that you need to close the intake valve earlier to build more dynamic compression. (The ZZ4 cam will do that) That being said you also want to open the valve fast to get air into the engine as soon as you can to maximize your power and torque output. You need to get the opening and closing points of the stock cam and pick a cam that closes the intake valve sooner or that same as stock but opens and closes it much faster then stock to allow as much air to enter the engine as possible. That means you need to look at overall duration and .05 duration and lift and installed CL to determine a cam that will accomplish your goals. The stock cam has slow lazy ramps that are designed to be easy on the valve train with no audible valve train noise. This does hurt down low torque production since no compression can be built until the valve if fully closed. Talk to a cam designer to have them help you since you do not have all of the necessary information on any of the stock cams to determine your opening and closing points. You need to study these numbers to pick a cam that will boost low end power yet still pick up the mid range torque that you desire. The numbers you have listed for cam specs are to generic to help you identify something that will accomplish your goal.
FYI, there is a very rare superram intake that was designed for LT1 engines, that would also help you.
a ZZ4 cam would help you with torque down low. To do what you want which is maximize low end power you need to get cylinder filling at low RPM to do that you need to close the intake valve earlier to build more dynamic compression. (The ZZ4 cam will do that) That being said you also want to open the valve fast to get air into the engine as soon as you can to maximize your power and torque output. You need to get the opening and closing points of the stock cam and pick a cam that closes the intake valve sooner or that same as stock but opens and closes it much faster then stock to allow as much air to enter the engine as possible. That means you need to look at overall duration and .05 duration and lift and installed CL to determine a cam that will accomplish your goals. The stock cam has slow lazy ramps that are designed to be easy on the valve train with no audible valve train noise. This does hurt down low torque production since no compression can be built until the valve if fully closed. Talk to a cam designer to have them help you since you do not have all of the necessary information on any of the stock cams to determine your opening and closing points. You need to study these numbers to pick a cam that will boost low end power yet still pick up the mid range torque that you desire. The numbers you have listed for cam specs are to generic to help you identify something that will accomplish your goal.
FYI, there is a very rare superram intake that was designed for LT1 engines, that would also help you.
I think this conversation has now come full circle AND it links up my other previous threads. What you have just stated, I am sure, GREGGPENN and others have already mentioned before. So now I have two of the same advice. Yeah, I need to talk to a cam maker in the future using what you all have given me. I am sure he can produce a cam that is like a ZZ4 but better tailored to my specifications. Now I need to research what other complimentary components I need that will help me in my quest to give my LT1 with it's stock intake the optimized lower end torque from idle on up. I think the DART heads I mentioned before are a good start and they are supposed to give excellent port velocity for low end torque production. Then, I need to figure out my exhaust set-up which I have in mind true duals linked by an H-pipe, unless this will be problematic.
Last edited by Phoenix'97; Nov 16, 2017 at 03:17 PM.
So yeah, above the short block do you think there's any similarity between an L31 5.7 and an L98 5.7? Hint: NO THERE ISN'T!!! I mean, aside from completely different heads and intakes they are exactly the same... So yeah, that graph has dick-all to do with how that cam would run in your LT1.
Holy ******* ****! This has NOT ONE GODDAM THING to do with an L98, TPI intake, or a ZZ4 camshaft!!! It's a ******* 350 with AFR 190 heads, a Lingenfelter cam, and a Stealth Ram intake!!! Seriously, what the hell are you talking about?
So, how do I achieve the results in the third and last torque curve graph of a 350 with AFR heads, a Lingenfelter 211/219 cam, and HSR intake with my LT1 and stock intake?
Well...this isn't the kind of powerband you've been blathering about! If this is the torque curve you want, then you sure as ******* hell don't want a TPI intake!!! But if this is the torque curve and powerband you want while keeping your LT1 intake, then you buy AFR 190 heads, a Lingenfelter 211/219 cam, and use your stock intake (possibly with porting)! You won't lose a lot of power compared to the HSR, and it will still fit under your hood. This just isn't that complicated, dude.
To the rest of you all reading all this and laughing at me: before you even bother to say you told me so, I already know you did...
Last edited by MatthewMiller; Nov 16, 2017 at 04:22 PM.
2020 Corvette of the Year Finalist (appearance mods)
C4 of Year Winner (appearance mods) 2019
Originally Posted by MatthewMiller
Holy ******* ****! This has NOT ONE GODDAM THING to do with an L98, TPI intake, or a ZZ4 camshaft!!! It's a ******* 350 with AFR 190 heads, a Lingenfelter cam, and a Stealth Ram intake!!! Seriously, what the hell are you talking about?
Well...this isn't the kind of powerband you've been blathering about! If this is the torque curve you want, then you sure as ******* hell don't want a TPI intake!!!
To the rest of you all reading all this and laughing at me: before you even bother to say you told me so, I already know you did...
Don't rag on yourself. Through some feverish internet hacking, I was able to turn on his webcam and see who we are dealing with!
Well...this isn't the kind of powerband you've been blathering about! If this is the torque curve you want, then you sure as ******* hell don't want a TPI intake!!! But if this is the torque curve and powerband you want while keeping your LT1 intake, then you buy AFR 190 heads, a Lingenfelter 211/219 cam, and use your stock intake (possibly with porting)! You won't lose a lot of power compared to the HSR, and it will still fit under your hood. This just isn't that complicated, dude.
Um, no, that is not what I want. Don't even try to pretend that you have my build nailed down when you are taking my comments out of context and misquoting what I said.
Oh, and my apology for screwing up on the graph when it was supposed to be for a ZZ4.
Last edited by Phoenix'97; Nov 16, 2017 at 10:46 PM.
So, how do I achieve the results in the third and last torque curve graph with my LT1 and stock intake?
That's a direct quote, and it refers to the graph from the 350 with AFR 190 heads, a Lingenfelter cam, and a Holley Stealth Ram intake.
Um, no, that is not what I want. Don't even try to pretend that you have my build nailed down when you are taking my comments out of context and misquoting what I said.
I used the wrong graph for a ZZ4 search I was doing. My mistake buddy. Get over it already and don't freak out like you are.
You quoted us the specs on that car! You knew exactly what it was, and you asked how you could get a torque curve like that! You're just wasting everyone's time. Which - surprise, surprise - everyone warned me would be the case. Someone needs to get out the ban hammer and eliminate your presence here.
Designer Imagines A Corvette That Looks More Like a Corvette Than the Corvette
Slideshow: A Jaguar designer's personal project imagines what a modern front-engined Corvette might look like if Chevrolet revisited the golden age of the Stingray.
