SS RRR

iTrader: (2)

What I suggested will do just that. Or, you can step up your game and get extensively ported heads, aggressive cam with high lift numbers on a stroker, valvetrain components to accommodate as well as driveline and you'll have the best of both worlds.

Shownomercy

iTrader: (1)

You know what would be better than making an LT1 into a dog of a TPI?

Throw a baby supercharger on it, run a few pounds of boost and get all the off idle torque you want, without the ruination of TPI esque mods.

SS RRR

iTrader: (2)

Honestly, I think I had already suggested that in one of many of these threads he's generated.

Phoenix'97

This is why there is a serious disconnect between what I am looking for and the suggestions I am receiving. Don't get me wrong, I appreciate them! It gave me plenty to research with what I was able to find and it helped me to do some soul searching about this build. Stepping up my game, as you say it, is not the path I wish to take. Another fear of mine is that the LPE 211/219 was tested on the L98 with the super ram intake and not the factory TPI intake which I plan on using for my build. I have no idea of how this is going to impact my total torque production and I don't want to have so much torque production mid-range that the tires simply lose traction in wet conditions. This is why I want to tone down the cam to having a lobe separation of 117 or even 118 yet having as much lift as can be given and spec'd appropriately for my unported stock heads modified to use up to 1.7 RRs. If the engine builder suggests I use heads with more flow then Dart heads will be in order.

I have considered superchargers and rear-mount twin turbos for this build. At a later date I MAY go with a rear mount twin turbo since this set-up was tested on a TPI Corvette back in the day and the results were big block performance out of a small block with what many considered a restrictive and pathetic intake. Even on it's way back down at higher RPM, the torque numbers were excellent! The way I see it, this is purely about how you look at it and what you want out of your application. I know what I want and the TPI intake is a gem in my eyes.


Yes you did and I thank you for all of your advice. I hope that everyone realizes that this is not a joke for laughs. I just got my factory GM Corvette TPI base in the mail today with the EGR tube provision unlike my whole TPI intake off of a 1991 Camaro with the 305 engine. All I need to do in the future is have a machine shop add material to the base and modify it to match the bolt holes on the LT1 heads, plus, a thorough degreasing and polishing.

Phoenix'97

I didn't realize this, but the cam I am interested in resembles that used for the LS7, although the duration I want to have kept the same as my stock LT1 cam, and naturally I lack the heads for such a cam, and I am looking at using 1.7 roller rockers with all the necessary modifications to my LT1 heads. The question then becomes can I use such a cam with my stock unported heads. If I can use a stroker with my stock heads then I don't see why I couldn't use such a cam with the valvetrain mods.

WSsixspeed

Phoenix'97

@WSsixspeed
Thank you for your comment, it was pretty much what I expected. I have been driving my Trans Am year-round and during the heart of winter for 10-years and I have a very good idea of what I am looking for and what would best suit this kind of driving where you are not supposed to see cars like mine driving straight in relatively deep snow. I can't enjoy street racing, especially when I have to preserve my commercial dirver's license which I worked very hard to earn years ago, and now I drive anything like it's a big rig, which I make good use of downshifting to engine brake to a creep before engaging my brakes at certain lights. To the point, I want to enjoy what you stated that the TPI can offer for my daily driving experience because I don't make use of higher RPM performance out of my LT1 and I could care less how many people drive by me on the expressway as a means to taunt me. I am there to enjoy my ride and cruise, mashing the pedal once in awhile.

On top of this, I am exploring what more I can do to scrounge out some more torque production out of my stock cam. Basically, I feel that 1.7 rockers with the necessary valvetrain upgrades and head covers will be the best I can do. Hey, it will be budget all right. Thanks again for your insight into what I should expect with the TPI intake.

Phoenix'97

Camshaft Shootout: Lobe-Separation Angle Tested and Explained
Quoting the article provided in the link, "To overcome this inherent problem in wide LSA camshafts, you simply need a higher-flowing intake port. This is why the LS series, and many other modern engines, can make great power on top and bottom with wide LSA camshafts and why a plethora of factory cylinder heads are flowing near (or above) 300 cfm."

So, I discover the flaw in my thinking that I could get away with using a wider lobe separation than stock. Ah, it is hurtful news but at least now I can focus more on the specs of my stock cam and whether or not increasing the lift and adjusting the duration amounts will give me what I am seeking.

SS RRR

iTrader: (2)

Phoenix'97

I have my concerns as to whether it is really what I want. The way I drive my car and everything about my stock cam that bothers me that I wish were improved upon, are really the performance goals I am seeking. I have no idea how an LPE 211/219 will work with a TPI intake on an LT1. I would be content with 1.7 rockers on my stock cam, or a 1988-1989 L98 cam made for my LT1, if it were to give me what I am seeking.

Shownomercy

iTrader: (1)

To throw more ideas at this convoluted plan.

I would bet you can achieve what you want via tuning it based on your driving contingents. Get the software, learn to use it, and start adjusting how the tune is at lower speed areas.

SS RRR

iTrader: (2)

You wouldn't want a 211/219 with a long runner intake. LPE also designed a 219/219 .560/.560 112LSA for TPI cars. They guy knew WTF he was doing when it comes to street car performance. Just getting that cam with rockers/supporting mods you would not need to worry about changing rear gears or stall, however for optimum performance you would want a step higher stall than stock and either 3.42's for an auto or 3.73's for manual and guaranteed your MPG would not suffer as long as it was properly tuned.

Phoenix'97

There is a problem, I am not set-up to change the tune on my car. Furthermore I don't have such knowledge to know what I would be doing even if I had the software to mess with my car. Also, what would be the benefit of trying to mess with the tune on my stock camshaft? Add more fuel for lower speed/low RPM conditions to give me the bump in torque I am looking for?


This is why I am being stubborn about the suggestions I am being given. The third gen guys claimed that the 1988-1989 cam with 117 LSA for the L98 actually gave the car a more enjoyable experience than the cams of the past at 14.5 LSA. This is why I am thinking that I have to stick with such a cam spec. The TPI has a definite torque peak and I have to keep that in mind when selecting a cam. If I use a cam designed to get a stock LT1 moving in a hurry, the added torque effect of the TPI intake will certainly produce unwanted results. I am only looking for an enjoyable street car with a wide cam that behaves like a tow cam at 1000-2500 RPM, compensating for the loss of airflow from the TPI intake before the runners start working to boost torque.

I am not implying that John Lingenfelter did not know his stuff, but he was not impressed with the stock TPI and designed the Super Ram intake, which trades up that mid-range torque that I seek for higher end torque. The stock LT1 intake makes higher end torque but has nothing mid-range, where my car does spend some time when I am flooring the gas pedal and letting off at 5000 RPM due to traffic conditions and speed zones. So, again, I have no desire to build my car to optimize upon what the stock LT1 intake will yield when the TPI intake is a perfect fit for my driving needs. I just have to figure out the cam situation and whether or not my heads will need more flow or not for what I am seeking.

Right now I am hovering around just having 1.7 rockers thrown on my stock cam. The 1988-1989 L98 stock cam was designed for the poorer flowing L98 heads and not my LT1 heads so I have to also keep that in mind. So, are the 1.7 rockers going to give me what I seek, "an enjoyable street car with a wide cam that behaves like a tow cam at 1000-2500 RPM", or do I need a custom grind with more lift? If a custom grind with more lift, similar duration, and 117 LSA will yield what I am seeking, will the current flow rate of my stock heads be fine or do they need more airflow? The stock TPI at best can flow around 195 cfm per grumpyvette's website. This is what I need to figure out...

dirtybob

read more
talk to a grinder about a custom camshaft
forget about LSA as an important criteria

https://www.google.com/search?q=site...w=1360&bih=595
http://www.speedtalk.com/forum/viewt...hp?f=1&t=52272

SS RRR

iTrader: (2)

I only read this part and believe this is the most important part of your post, and the answer is, you will notice no difference between stock and 1.7 rockers on your stock cam. There may be some power improvement. Rule of thumb, with supporting mods, is around 10rwhp with added 1.6 rockers, but usually those who've done this also had an off road y-pipe. As I said, the only way you are going to know is if you commit to whatever has been suggested on your many threads and experience it for yourself.
I am not sure if I have mentioned this before, but if you have the funds, you can always do a head swap with 1.6 rockers and retain ALL stock driving behavior with higher power/torque curves. I can't speak for any other head than the LPE's. When I did my heads only swap with 1.6 rockers, Edelbrock shorty headers into stock exhaust with cats it went from 282rwhp/300rwtq to 310/310. Stock the car did 13.9's @ 99/100mph at a certain track (all time best was 13.6@102 at a more sea level track) to 13.2's @ 106. The power and torque curves behaved exactly the same as stock, just at a higher level. All this was done on the stock tune. If it were me, that's the way I'd go. I would much rather do a head swap than a cam swap, but that's just me.

Phoenix'97

Thank you. I will check the links out.

The thing is, I have been reconsidering what was suggested to me in the threads of the past. I am learning as I go, I am making mistakes in my thinking when I don't fully understand all the facets involved, however I am getting closer to what I am looking for with this build. Yes, maybe I am wrong in my thinking about wide lobe separation and more lift but suppose I do decide to take out the additional loan money for a head upgrade to what you suggested, are we talking again about increasing airflow to boost performance out of a stock cam? This seems to be on par with what I was thinking earlier but not being sure if I needed more airflow out of the heads which has me thinking about 200 cfm and perhaps using the cast iron LT1 heads with modified valvetrain for the 1.7 rockers. Since I will now be using better flowing heads with upgraded valvetrain, why not go the extra mile with a custom grind to get as much lift as the heads will allow and working with the rocker ratio?

StealthFormula

iTrader: (35)

Phoenix'97

When you are stubborn you tend to overthink a lot. I also hope you understand that I won't ever sell my car, besides she lost her value a long time ago and continues to do so, until I can have the car made anew by a shop like Kindigit Designs or Classic Car Studio, hence the need to take out a loan! I really can't trust any shop in my area.

I appreciate your advice and I will consider it if I have my proof that what I cam considering now with the rockers is not going to cut it.

Phoenix'97

I feel my car is perfectly fine with it's stock gear ratio. I don't wish to change it as I have spent around and over 10-years driving with it. I still wish to bump up power on my LT1 and try to address the desire for more torque off-idle and up to 2500 RPM without using a dedicated tow cam after learning how they behave. The only other path to take if not mechanically improving torque out of my LT1 is to put on an intake and use fluid dynamics to give me what I am seeking.

I found an article doing a search and it confirms what SS RRR was telling me about the need for better heads that flow more air. As I suspected, I need better flowing heads but how much for my stock cam with 1.7 rockers, given that now I realize this is probably as far as I can go with the combined lift at the rockers.

1.7 Roller Rocker Considerations

So, I need to really look into this and whether or not I can get away with dirt cheap stock cast-iron LT1 heads and whether 200 cfm will be enough.

Phoenix'97

@KW Baraka

Thank you for your comment. I am trying to stick with what works, or rather, what I am used to with my car that can possibly be improved upon. The wider LSA is contradictory to more low end torque production but the wider LSA has been claimed to work well with the TPI intake and the wider LSA is the stock spec for my LT1 which I want to preserve. Again, I am assuming that I can bump up my power level down low and mid-range by using 1.7 rockers and possibly having my stock camshaft advanced four or as high as six degrees, so long as this does not pose any serious problems with clearance of the intake valve with the piston head. The power produced won't be much but I am basically looking for a torque shift where I am producing the torque number at 2000 RPM stock down at 1500 or preferably 1000 RPM with the new modifications. The rest of the power will come from a compression increase and depending upon whether I decide to go with stock cast-iron LT1 heads with the necessary valve-train upgrade.

As per the article,
Performance Rocker Arm History

"The advantage of using higher ratio rocker arms is that the same cam lobe profile can produce the total valve lift for more power... How does changing rocker ratios affect the duration of the camshaft? Because the cam lobe is still the same, the point where the cam starts to move the lifter is still the same. The same is true for the closing side of the ramp. But, the rate at which the valve opens is now somewhat faster because of the higher ratio of the rocker arm, so the effective duration of the camshaft is increased slightly – maybe a couple of degrees in the above example... A small ratio change won’t have a big impact on the rpm range where the engine makes power, or its low end torque, idle quality or the amount of intake vacuum it produces. But, a large change in lift ratio that increases mid-range duration significantly will move the engine’s power peak up the rpm scale. That’s why wild cams with lots of duration and valve overlap that produce tons of high-speed horse power are typically bad for low end torque, idle quality and everyday drivability."

So, the downside to this brilliant idea of mine is that I am now defeating the purpose behind my goal to increase low end and mid-range torque using my stock cam when the 1.7 rocker ratio in essence will shift my torque curve up the RPM scale versus down where I want it. So, I am going to need to consult a cam designer after all. I want the added airflow bonus that will come from 1.7 rockers but I am going to have to have the cam duration decreased to match my stock cam duration and at a lobe separation of 117, unless going as high as 120 will yield better results with the higher compression and torque peak of the TPI intake.