alot of other things can play into that...same track? same weather? and you should have...at least if they were stock, a better launch with the 87, if tires, weather, trannies etc. etc. were the same. Once again we can look at 205 HP at 4300 RPM for the 84 vs. 240 HP at 4000 RPM. Don't get me wrong, I have absolutely nothing against a CFI. Look at your time difference (.448) just under a 1/2 second difference.....in the 1/4 that's alot of time.

 

CFI Intake "options" include porting (essentially free), Xram, Offy, Sy-1, w/lids. All of those run ABOUT $400.00. So to change a cross ram intake to another, much better flowing cross ram intake (so you can still call it a "CFI" w/a straight face), will run under $500.

Upgrading a "TPI" in the same fasion, to something that flows better and still be able to call it a "TPI" w/a straight face, means about $1000.00, for a base, runners, and plenum.

That's correct.

Lets see you "port" some of those stock TPI runners. I want to watch that. As for siamesing the BASE runners, same thing can and has been done w/the CFI intake. IOW, both intakes (with porting) have the same basic problems, and the same ultimate potential; fully ported and siamesed. Actually CFI has more, because you can also shorten the runners, which you can't do w/TPI. Once you reach the limit of the stock pieces for both designs, at around 350hp, then you need to buy a new intake, and a single piece CFI replacement (even with custom lid and the two injectors) is cheaper than a replacement TPI assembly. And 8 injectors. And a MAF. And a tune, And, and, and...

 

I don't believe that anyone posted that a stock CFI will match a stock TPI. You haven't posted anything new in your above post. The discussion started with the statement that:
Which is true. For s-load of money, time and effort, a direct swap of a TPI intake onto a CFI engine would net 20 - 25 hp, and that is NOT worth it...at all. For NO money, the same person could port their CFI and gain the same 25 hp (or more). So post #8 that started all the debate in this thread was accurate, and good advice. You can get to about the same point w/either intake. So why spend the money, time and effort changing to a system w/the same or similar ultiamte limitations?

 

The intake is on the work bench and porting has begun. I had no idea you could gain 25 HP from porting the intake.

 

Quite honestly I have no idea what it would cost to swap from a CFI to a TPI....but an increase of 25 hp and an et gain of what? 1.4 seconds at a lower RPM range seems significant to me...granted you can pickup some horses from the CFI by porting it....same is true for the TPI, maybe the increase would be less than what you'd gain from porting the CFI...but your still playing catchup. As far as time goes, heck it wouldn't take much, what have you got? two MAF sensors, a TPS sensor, a single IAC, a newer ECM...given the MAF, IAC and TPS are all mounted to the intake it's just a matter of the ECM change and a little wiring, very little cost for the Two MAF relays, maybe a few other insignificant items. I could definetly be wrong about cost for a used TPI, think for the heck of it I'll do a little research there...for fun. I do want you to know I'm not at all knocking the CFI......I just think the TPI was a significant improvement....even if both have there limitations....like everything else. Heck, I really enjoyed my days of modding and rodding, but I really think at 63 there over. I just happen to like vettes.

Just looked at one complete TPI setup in the FS section from RichS....$300. for everything including 8 newer injectors....at 50 PSI I'm not sure what we could do with those lol. So figure another $100. for the ECM, $40-50. for relays, another $100. for gaskets, wireing etc. what is that $550-600. might be pushing it, but still for a 1.5 second better ET,without porting the intake, still not a bad increase for the $$$ considering what a mini or super cost, plus they're not much advantage without cam and heads.

 

When I first got my CFI I did think about the coverting it to a TPI, after I priced all the materials,my time and saw what was involve in converting the harness I said to myself no way. I estimated at the time it would cost me at least 1000.00 and that didn't even include my own labor

Due to my experience at the time I didn't trust myself with porting so I choose the xram. Cost was $450 and that option looked much better in my eyes it only would take a few hours to install. They say that without doing the bottom end the xram is close to porting the orginal intake. If thats the case my dyno sheet in my corvette pics shows 207 rwhp. An I could have gotten more out of it if I had understood the CFI a bit better, the car was running very rich. I was told that I should have been closer to 230rwhp. But who knows I never had a chance to change it to find out.

So a stock CFI at 205 at the flywheel with a 15% drivetrain loss would give you 172.25 rwhp, mine was 207.7 Thats almost 35hp increase. And I only spent $450... much rather spend that than the thousand I estimated. Plus when and if I need to get more fuel flow through the TBs there's a couple of easy solutions. Since that time I've put heads and cams in and haven't had it dyno yet and still using the orginal size TBs

By converting to TPI what hp gain are you guranteed? Would you rather spend $750, $450 or $0 for the same gain.
Once the top end is done on either CFI or TPI (l98) the bottoms are pretty much the same.

 

The POINT is, you can get that same gain for nothing but labor and gaskets w/the CFI intake. OR you could spend $90 on a summit cam, $125 on 1.6 ratio Summit rockers and get more than 25 hp. Here a guy spent, what? $1050.00 for .2 on a TPI set up:
http://forums.corvetteforum.com/show...76&postcount=6
And here are similar results from about $700.00
http://forums.corvetteforum.com/show...61&postcount=7
-This is all steps one might need to take AFTER spending the above estimated $550.00 just to get a TPI.

I guess this debate is getting pointless. All the facts and evidence have been presented. Now it's a debate about wheather or not "at your age" or "with the money that you make" or whatever aspects of your life affect your modding decisions -make it worth grinding, or spending money. The FACT is, that w/$40 bux worth of gaskets and some grinding (enough to make the runner cross section the same as a stock TPI's runner), a CFI car will match the TPI car. If both are ground to the limits of their castings they are still going to be competitive w/one another.

Now for ME, in MY life, I can still grind, and I'd prefer to over dropping ~$550 on an intake, to get to the same place. On my current '06, if I could do the kind of mods to it myself, by hand, that I did to my CFI car, I would in a heart beat. Unfortunately, in the case of the LS2, GM didn't cast one single part, completely f'ed up, leaving tons of power on the table for a handy die grinder. Unlike the L83 (or LU5 in my case).

The REASON why the CFI is down on power and tq compared to the '85 TPI is the runner cross section. That is it.

 

Amen. I'd like to see what a TPI or LT manifold would run like if it had only 2/3 of a runner. The facts are that a Xfire can be made to run with "newer technology" cars using a bit of elbow grease and bringing the components up to par with what the newer motors have.
Like roller cams, good flowing heads, better exhaust and tune. When you've done those things, the Xfire holds its own. The superiority of the newer Gen motors wasn't ONLY because of the manifold. End of story.

TomCFI,

I've now graduated to GMs other DIY project, the LT5 motor. Oh! And this one definitely traps higher than an LT4

 

You can't port the TPI the same as a CFI, because the TPI doesn't have the added in restriction to get rid of that the CFI has.


Two tenths of a second for $700.00 and $1050.00? For under $1500.00, probably closer to $1200.00, of which 75% ± is torque converter, I have cut my ET by 2.0. Not .20, but 2.0. No cam, no headers, no heads, no injectors, no fuel pressure regulator, no air foil, no gears, no... Intake manifold porting only.

Just to set the record straight, it wasn't me that said a stock CFI was faster than a stock TPI.

And by the way, for those so inclined, when pricing out your CFI to TPI conversion, don't forget the fuel pump.

RACE ON!!!

 

I only run at the same track and every year and yes,weather is similar because I get DA readings from the track tower. I have a log book of every track outing I attend. It was a great comparrison and a half second is about 2-3 cars at the speed.

 

The sad thing is,every CFI guy can do what you did,they just don't I really don't plan to mod my 84 but If or whenever I do its a simple desicion of what to do. porting,converter and tires

 

Anybody know if there is a weight difference between an 84 and an LT car. I know my Xfire weighed in at 3200lbs w/o driver.

 

That's sweet, Dom. I have alwasys respected and liked the LT5, and it's definitely a DIY engine, which I like as well. Have fun w/that thing! I have "graduated" too, but on my car everything you do to it cost $1000 bucks. Headers are a grand. Intake is a grand. Cam, springs and retainers is a grand. Shocks are a grand. Mufflers are a grand. It's lame, and I miss the value aspect of my F-bodies (and the Gen I SBC).


I believe that the mid '90's cars are around 3400 lbs.

 

Well let me tell you ZR-1 parts are like that too. $1500 for headers, plenum is about 750. Getting the heads ported is $5000.
Anyway, its a beautiful motor. Nothing like it at full wail at end of
1/4mile. Its only getting going at 1/8. And its only a 5.7L.
My other thought was either an MR on the Xfire or trying the LS transplant into the 84. But at the end of the day it still won't be a ZR-1.

 

You are absolutely right. I haven't done a thing that you nor anyone else can't do. I may have persevered to a greater degree than some, but there is no magic under my hood. Air fuel, spark, it's all just the basics. That is why I have to laugh at a post like, "The sputum that you post is hilarious and good entertainment about your CF. People that post like that are either ignorant on the subject or don't have the motivation or energy to unlock the performance is laying at their feet. Since they didn't produce similar results, someone that says they did, must be lying. What is "hilarious" is the "sour grapes" thinking of such an underachiever.

RACE ON!!!

 

Man, I can't believe this thread is still going and unlocked. I quit reading the bench racing and name calling atleast a week ago. Lets face it, the CFI is not the worlds best intake. In fact, it may be one of the worst intakes ever on a vette. Please don't misconstrue that as a boon for TPI. The 85-89 TPI intakes weren't much better. Similar limitation; airflow. In fact, I don't think anyone on this board is ever really satisfied with the stock parts on a vette. Even the LT5 guys are questing for more HP and their cars breathe like they got extra lungs. If you like your TPI, great. Mod it to your heart's content or keep it stock. If you like Xfire, great. It's a fine system, I'd even go so far as to say a touch more reliable than TPI when kept properly maintained (fewer injectors, fewer failure points). I really can't believe this is still being debated.

 

You are preaching to the choir. I don't think anyone in this thread has said any different.

RACE ON!!!

 

 

I told you NOT to take the lid off of my air cleaner!

RACE ON!!!

 

What am I looking at?