| Author | Message | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 850 Registered: 11-2002 |
It will have to be built, no big deal. What's your timeline? Straight cut will whine like a full race gearbox (not louder than the exhaust though) and be strong enough for over 1000 ft-lb. Helical will be quieter and strong enough for what you want to do. Let me know. | ||
| Rick Doria (Zsnnf)
New member Username: Zsnnf Post Number: 12 Registered: 9-2003 |
Rob, Do you have a taller drop gear or do you need to design one? Yes my car was built Jan '92. Thanks again, Rick | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 847 Registered: 11-2002 |
Rick, A stock F40 will do 200 mph in good condition. I helped design the 'quicker' ratio eight years ago and I can do the 'taller' too. The lower ratio was in responce to the fact that the car I built for a customer was modified for road racing and Road America was the fasted track, so I geared it for about 175 mph with the slicks we ran at that time. One more bit of information after reviewing notes: You'll have to verify your R&P. You are likely to have the 11/30. I did on the 1990 car, othewise you're right, 195 mph. 4200 in 5th on my sheet is 105 mph with 10/29, 112 mph with 11/30, so looks like you have later US production. Do the drop gear change. | ||
| Rick Doria (Zsnnf)
New member Username: Zsnnf Post Number: 9 Registered: 9-2003 |
Rob, I believe the Euro cars with no Cats had an 11/30 Bevel gear ratio. (according to my shop manual anyway)  My Owners manual claims a top speed of 194mph with the 10/29 gears the U.S. cars come with. At 100mph in 5th gear I am turning about 4200rpm. If I were to try and do 200mph with this gearing it would take over 8400 rpm. A little high I think. Does this sound right or has someone installed drop gears in here all ready? I went over to Caribu and talked to Tate yesterday. The Drop gears they sell make the car go 9% quicker, not faster. We also discussed the LM turbos and chips they sell. He also said you *may* still have your stock chips. If so, would you be interested in renting them out???? Is there a set of drop gears available to make the car go faster? Right now I am trying to sort out the rich mixture and see how much H.P. it will make. I believe this car should go 200mph with anything over 425rwhp. Thanks for your repsonse, Rick | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 845 Registered: 11-2002 |
I can get the drop gear, too. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 844 Registered: 11-2002 |
Dear Rick, Stock drop gear is 21/28, no? With the oem size tire, this yields over 200 mph. I know 'cause I was involved with C+D's test at Ft. Stockton with one of the first F40's in the country (a bone stock car). I think the issue is August 1990. Average was 198+, but the car did 202, and seemed capable of a couple more mph. I would not build a new ring and pinion of 11/30, stick with the 10/29, change the drop gear to a srtaight-cut or helical-cut 22/28 if you want a tad more gear. It's much easier, much less expensive. As for brass or plastic valve, the plastic is the OEM piece, and it's good at what it does: fatten the tourque curve. The brass one would indicate your car was previously modified. I can't verify the chip information as I'm on the road for another week and don't have complete resources with me. What's your modification goal? A totaly stock, in good condition F40 will run 200 mph. How quickly do you want to get there? I've done the big turbo, track-only modifications to make an F40 significantly quicker, both in longitudinal and lateral acceleration. Let me know. Best regards, Rob | ||
| Rick Doria (Zsnnf)
New member Username: Zsnnf Post Number: 5 Registered: 9-2003 |
Tim, Yes, That's me. Jeff Smith at Chevy HP has always been very good to us. Did you also see the pictures of the crash while we were on a 203mph average run? Part of the reason I am trying to sort this F40 out is to make a recorded 200mph run in an open road race. European Car is going to carry the story. We will need an 11/30 bevel gear for the trans if anyone knows where we can get one. Rob, I took a look at the ECU. It appers to have the Magnetti Marelli decals over some of the bolts still on both sides of both ECUs. Maybe they were removeed and reinstalled carefully. There is a piece of masking tape on the inside of the interior covers that the ECUs are under that says FNP 62533200. It looks like someones name and initials are after that. Is that from the factory? The ECU's also have the cars serial number written on them in felt pen. As far as the chips go, there looks like there is a piece of clear tape on it with 4F 07 50C 11 written on it. Is this a factory chip? Can the factory chip be reburned? As far as the Air recirculation valves go, mine are plastic, not brass. Should I get brass ones? If so, From who? This sure is a steep learning curve. Thanks again for all your help, Rick | ||
| Tim N (Timn88)
Advanced Member Username: Timn88 Post Number: 3469 Registered: 6-2001 |
Rick, when you mentioned your 230mph open road racer would you be refering to your corvette that you run in the silver state classic? your name sounds familiar, from an article in i think it was GM high performance a few years ago. | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 841 Registered: 11-2002 |
Rick, I'll answer your email here if you don't mind. 1. Yes 2. 5 psi, meaing you're really at 21 psi on a real gauge: you'd better verify A/F ratio assuming it's the OEM chip in the ECU 'cause you've leaned it a bit with the exhaust change. But... see #4. 3. Idle is adjustable, 100 rpm is not a big deal, but you may have reason to go into the intake so reset it then. 4. I strongly beleive you have aftermarket chips in the ECU, likely to be sourced from Performance (something or other I can't remember) out of Florida I think (I'm out of town away from my other resources). This specific chip was developed and burned for the Sultan of Brunei in England in 1989-90. It plays it very safe by adding tons of fuel so owners can wick up the boost and no one will blow due to lean conditions. The chips came with a brass valve to be installed in place of the OEM solenoid valve between the intake and wastegate. A car with this chip will have black exhaust at full throttle due to rich A/F. Take a peek at the chips in your ECU, easy to do. Best regards, Rob | ||
| MarkPDX (Markpdx)
Intermediate Member Username: Markpdx Post Number: 1014 Registered: 4-2003 |
Rob - If I Remember Correctly | ||
| Rob Schermerhorn (Rexrcr)
Member Username: Rexrcr Post Number: 836 Registered: 11-2002 |
IIRC? I don't know that one. Stock boost is 1.1 bar (16.2 psig, 30.9 psia, 16.0 kg/cm2} When intake manifold pressure exceeds about 21 psig, the ecu hits a fuel injector cut-off, not a BOV or wastegate dump. That's why it's soooo harsh, no fuel, no power. Agreed. At WOT. Hit the nail on the head here. Too much tweaking without proper knowledge. All good info in this thread. If you're hitting the fuel cutoff, the OEM solenoid valve between the manifold and wastegate can be tuned. It should be retained for improved drivability in moderately tweaked applications. If you're going wild with boost, you already know what to do with this plastic variable duty-cyle valve . Rob | ||
| Rob Lay (Rob328gts)
Board Administrator Username: Rob328gts Post Number: 6506 Registered: 12-2000 |
Chris Parr really needs to see this or even Roland. I know Chris has done many dyno runs and Roland probably has too. | ||
| Steve Barker (Steveb)
New member Username: Steveb Post Number: 4 Registered: 10-2003 |
Rick, I hope you plan on posting your new numbers here after your next dyno session. I am curious as to the answer to your question on how much boost you should have. I gather from your original post that you have not dyno'd with the test pipes installed and your motor making 20psi of boost. Does anyone know how much boost these motors can "safely" handle? Steve | ||
| Ben Cannon (Artherd)
Intermediate Member Username: Artherd Post Number: 1032 Registered: 6-2002 |
Rick- you have bad cats! Keep the test pipes! F40s IIRC should make around 18-19lbs of boost, then the BOVs go. 10:1 is way rich, even turbo motors should be in the 12.0:1 range over most of the band. I know the F40 has a reputation for going out of tune relatively easially, or at least many of the cars have been tweaked with improperly. A good mechanic with F40 expierence should be able to sort the car and establish a baseline for/with you. PS: be VERY careful running lean under boost. That's how turbo motors die. Best! Ben. | ||
| Rick Doria (Zsnnf)
New member Username: Zsnnf Post Number: 3 Registered: 9-2003 |
Chris, Thanks for the input. We are going to the dyno again tomorrow. I have read the shop manual and can't find how much boost this SHOULD be making. It has gone from around 14-15psi with the stock exhaust system to 17-18psi with a Tubi muffler replacement to over 20psi with the test pipes installed. When the cats were still on, the Overboost light came on around 17.5psi, now at 20psi it is not on. Any idea on what conditions need to be met to turn on the overboost light? How much boost should the engine make? How much RWHP? Thanks again, Rick | ||
| Chris Burch (Cyb)
Junior Member Username: Cyb Post Number: 55 Registered: 1-2003 |
Rick, I have had to tweek my pop off adjustment on my F40 everytime I make a change. IE new exhaust, lighter flywheel etc. etc. You may have a hole in the diaphram of your pop off valve resulting in a loss of power. Ideally, you want to be pegging the boost gauge at redline in every gear. You might try turning in the hex nut on the back of the pop off valve 1/4 turn and testing from there. By turning in in, it will bring the boost up somewhat quicker each turn. Trial and error, but it works! | ||
| Mitch Alsup (Mitch_alsup)
Intermediate Member Username: Mitch_alsup Post Number: 1159 Registered: 4-2002 |
15 gallons of 91 octane and 5 gallons of 100 octane will give about 93.25 octane ((15*91)+(5*100))/(15+5) = 93.25 I also agree that you are way too rich, and would shoot at 12.0-12.5 at peak TQ and closer to 12.5 at peak HP. However, since you got 25 HP from 2.25 octane increase, you should try 95 octane to see if even more HP is available with gasoline selection. | ||
| Steve Barker (Steveb)
New member Username: Steveb Post Number: 3 Registered: 10-2003 |
Rick, Thanks for the offer. I currently have a 360 Spider that I am selling through Ferrari of Seattle. When it is sold then I will be searching in earnest for an F40. I have bought 3 Ferrari's through Ferrari of Seattle and they are great to deal with. Because of the way they have taken care of me, I want to get my F40 through them as well. Steve | ||
| Rick Doria (Zsnnf)
New member Username: Zsnnf Post Number: 2 Registered: 9-2003 |
Thanks Guys, I agree with the 11.8/12.4 to 1 air fuel range being what it should be. We tune my 230 mph Open Road Racer there, it has 13-1 compression, and it runs fine on 100 unleaded 76. I have only had this car about 6 months, so I was real disappointed when it started to go soft on power. I thought maybe I was just getting used to it. The Cats look O.K. but I still wonder why the engine is tuned so rich? Are they this way from the factory to be safe, 0r has someone "tuned it" this way? It will be interesting to see if more boost has created a leaner mixture. Steve, What are you looking for in an F40? I know of a few for sale. Thanks again everyone, Rick | ||
| Steve Barker (Steveb)
New member Username: Steveb Post Number: 2 Registered: 10-2003 |
Allan, At the risk of giving you more info than you might want, here goes. I am using a NOS Double Cross plate system that was flowed by Applied Nitrous Technology. There are 4 levels to this system and the 1192 was on the 4th level. I have two videos posted that show two of my nitrous runs - I have made over 30 with nitrous and over 200 naturally aspirated. The first is 1143rwhp and the second is 1192rwhp. Within 2 days of posting these there were over 8000 downloads. Not bad for files that are over 20 meg's. After 1 month there were over 25000 downloads. I have no idea how many have been downloaded by now. These numbers are with a full 3-1/2" oval exhaust system. The 1192 rwhp equates to 1413 hp at the flywheel! My combination loses 15.6% through the drivetrain. I know this because I dyno'd the motor on an engine dyno and then immediately put it in the car and made runs under identical conditions. Let me know if you want a link to them. Steve | ||
| allan fiedler (Allanlambo)
Intermediate Member Username: Allanlambo Post Number: 1189 Registered: 6-2002 |
Steve, how much Nitrous are you running through your motor to make such a massive difference in rear wheel hp? | ||
| Steve Barker (Steveb)
New member Username: Steveb Post Number: 1 Registered: 10-2003 |
Rick, I am currently in the market for an F40 so I don't have any experience with one. However, I do have experience with high horsepower cars. I have a 67 Sting Ray that is street driven and makes 1192 rear wheel horsepower with nitrous and 714 rwhp naturally aspirated. I also have a 1990 Callaway Twin Turbo Corvette that makes 607 rwhp and 735 rwtq. I have my own DynoJet chassis dyno that I use the heck out of. I have made over 75 runs on my Callaway. I have a Racepak data acquisiton system that I use to gather data with each run as well as air fuel ratios. The following information is based on my experience and might not necessarily agree with what others have found. You are right that 10.0:1 is WAY too rich for a turbocharged motor. When you see 10.0:1 it really means that the air/fuel ratio was 10.0:1 or lower. 10.0:1 is the lowest that it can record. You might have 9.0:1 or worse. I would shoot for a ratio of between 11.5:1 and 12.0:1. This is where I made the most horsepower on my turbocharged motor AND on my nitrous motor. I hope this helps. As soon as I can find a good F40 I will put it through its paces on my DynoJet. Steve | ||
| Philip Airey (Pma1010)
Member Username: Pma1010 Post Number: 469 Registered: 7-2002 |
Rich running will kill the cats quickly. Whether this clogs them or burns the honeycomb I don't know. 10:1 sounds terribly rich. I don't know the factory specs, but with high boost turbo apps elsewhere, we used to aim for about 12.5:1. | ||
| allan fiedler (Allanlambo)
Intermediate Member Username: Allanlambo Post Number: 1182 Registered: 6-2002 |
Maybe your cats had gotten clogged? | ||
| dave handa (Davehanda)
Intermediate Member Username: Davehanda Post Number: 1962 Registered: 5-2001 |
You need to speak to Chris Parr, he has an F40 (LM?)...he has done a lot of dyno runs...you might search for his posts in the archive. | ||
| Rick Doria (Zsnnf)
New member Username: Zsnnf Post Number: 1 Registered: 9-2003 |
My F40 has been feeling a little slow lately, so I decided to take it to the dyno to see what was up. Does any of this sound NORMAL for this car??? Our first pull was a very disapointing 345RWHP making about 14-15 pounds of boost. The car had 15 gallons of 91 octane fuel in it so we thought we would try some 100unleaded 76 race fuel. We added 5 gallons to what was already in the tank. To our suprise RWHP jumped to 370. Better, but not what we thought there should be. We removed the stock muffler. Power jumped to 410RWHP. We installled a Tubi muffler and it went back down to an even 400rwhp and boost was up to 17-18 pounds. We just installed "test pipes" in place of the cats and boost is up to about 20 and the car feels great. It breaks the tires loose at the top of 1st gear and gets sideways at the top of 2nd like it used to. We have not redynoed it yet but plan on doing so this week. This decrease in power has taken place in the last 700 miles. The car has 28,000 miles on it now. Also, the air fuel meter on the dyno shows richer than 10 to 1 above 3500rpm. I *think* this is way too rich and more power can be had by running a leaner mixture. Is this mixture right? How much power *Should* this car make? I appreciate any of your thought on this, Rick |