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MG MGB GT V8 Factory Originals Technical - Dyno set-up?
| Hey all. I have not had the car on a dynoe before. I am wondering how they typically hook up a MG to a chassis dyno?? The frot is easy enough using the frame loops from the factory but what about the rear?? Do they just wrap around the axle and brake line??? I have a dyno sessionsSat and just realised my car is different than the others attending and want to get a solution before I head out there... |
| Larry Embrey |
| Yoy might want to try what I do when I transport the race car. 1/4" thick piece of flat steel, drilled with 2 holes top pickup the rear of the U bolts. A third hole that I drop a screw type chain link into. Basically a trianular piece so the chain link clears all rotating members |
| greg fast |
| I THKN I know what you mean. Do you by chance have a picture?? I also need to make sure it can handle geting hit with an extreme amount of stress, I don't to kill anyone if my car comes off the rollers.. |
| Larry Embrey |
| Larry, I can't answer your question, but maybe I can help put your mind to ease. At the British V8 meet last year, the chassis dyno guy had no problems making runs with MGBs, nor was any damage done to them. The dyno he had was not particular setup for MGBs, but he had no trouble with it. Maybeo some of the guys who had their cars dyno'd can give you more details. |
| Dan Masters |
| Sorry Larry, no pics- and no digital camera. I'll try to mosey out to the barn tonight and and use my 'phone-cam' and see what turns out- but it's really simple. Just a chunk of 1/4" thick steel flat bar or plate, shapped like a triangle. A hole in each corner- 2 corners pick up the rear legs of the Axle U-Bolts, the third is drilled to accept a 3/8" threaded link for a chain. One leg may need to be relieved to clear the lower spring plate- depends on what shocks you have. Can it handle stress- well, I was towing the car on my car trailer. 10 miles south of Mesquite Nevada, my trailer was bumped by the rear wheel truck on the rear trailer of an 18 wheeler. This slammed the trailer into the k-rail on the lh side of the passing lane, and pulled the back of the Bronco over about 2 foot. The setup jack-knifed, and the only reason it didn't flip was it skinned the tires off the rear wheels of the Bronk. When all came to rest, the front of the car had shifted where the right front fender hit the spare tire carrier on the Bronk and then shifted to the other side of the trailer so the left front wheel was actually hanging off the trailer. I saw no evidence of deformation or failure on the plates. Still use the same ones. Tough enough? |
| greg fast |
| Larry, My car (with the least HP) was one of the ones put on the chassis dyno that Dan mentions. As best that I can recall, the cars were only chained under the front end. I'll have to check to see if I shot any video of one of the dyno runs. |
| Carl Floyd |
| Call me REALLY silly. sure enough the MG DOES have chassis eyelets on the rear just behind the shackles.. Car ran "OK" I have allot of tuning to do, and I ran on a Mustang dyno which kicks out markedly lower numbers.. 195rwhp 234rwt That is with STOCK rear end and gears which also mess things up a bit.. The mustang drivers at the dyno were all pretty shocked.. heh Many of them were only 203rwhp... |
| Larry Embrey |
| Larry, What do you mean that Mustang dynos show low #'s? You can either spin the rollers or you can't. Are you saying that there is no standard in the dyno world? I have only seen pictures of the process, but if there is no standard, why bother with the test? What gear did you use for the test? What was the ambient temp? How did you cool the engine? I bet it was fun to do, especially with some of the "big brother" cars tested at the same time. Chris |
| c l sorenson |
| There is no standard. a Mustang dyno is a rolling road type dyno that varies the resistance on the vehicle based on it's weight and drag. It loads the vehicle like on the road in the real world. The Dynojet Dyno is just a big 3000+lb disk and acts as an accelerometer. It does not vary drag or load on the car. The Dynojet typically will produce numbers ~10% higher than a mustang or load based dyno.. I mad 2 runs back to back, no shutdown, maybe 1-2 min idling between runs. The car was at 190* starting 1st run and was around 200* at end of second, so I would say my cooling is working ok. within minutes of pullout off dyno and going down street she was cold and the Therm had shut again Temps were low 30*F. It is recommended you use the gear in your trans that is the 1:1 ratio for the test. The reason to bother is not really to have a true exact number for to compare to other people, but more so you can benchmark what changes to tune and parts due to performance. Also the load based dyno lets you load the car and tune it so it will run great on the road.. |
| Larry Embrey |
| After a few runs and $$$ on the dyno I decided to buy a G-tech and a Escort to check changes that I do to my engine, 1994 302 Ford FI/1968 MGB GT The G-tech was off by 2 hp from the dyno #'s the escort by 2 1/2 I used them both. The pulls are done in 3 gear. Testing with these meters in the real world is what really matters, such as air intake chnages that can not be measure in a dyno with the car seating still. # will change with cooler air etc. What really matters is the torque and 0 to 60 times when testing, hp is for.....those who like hp #. |
| 255 rw hp |
| I can't say I agree 100% with that. Tuning using a LOAD BEARING / Rolling Road dyno with WB can't be replaced by a G-tech. Geting A/F right is critical, even in a FI car like yours and mine.. What trans are you using?? On the dyno they always recommend to pull in 4th as it is the 1:1 ratio in modern 5-spds.. I would like to see pictures and info on your car for the website.. drop me an email... |
| Larry Embrey |
| Your fellow countryman Mr Shelby had a saying ; 'Horsepower sells cars, torque wins races ' this is being bourne out in Europe where turbo-charged diesel cars are now often faster in mid range than petrol ones. I find the big attraction of the Rover V8 engine lies in its torque, I have re-timed the camshaft and fitted modified induction to improve torque, my RaceTech performance meter only credits me 160bhp at the wheels, but I get regular 0-60 times of 6.6secs. Can rolling roads measure torque, or do they just gine HP ? Mike |
| M Barnfather |
| M Barnfather How did you re-time the camshaft? and what did you do to the induction? All sounds very interesting. mark |
| Mark |
| M - They do both, and you are correct in that assesement... Torque moves mass, HP just keeps it moving... Drag racers know this all to well, it takes torque and proper gearing to get you off the line, HP is for 1/2 track and beyond... The 302 is a real torque monster.. my numbers were 195hp/234lbft at rear wheels.. so regearing the car quite a bit will make my car wicked fast and hopefully help keep the tires planted a bit more.. I am not sure what is out there for the Buick/Olds/rover crowd but there are widely available aftermarket timing chain assemblies that let you alter the camshaft timing.. IIR, retarding the cam builds Torque, but you have to be carefull about valve/piston clearances when altering timing of the cam.. As for induction. From my basic understanding from whatching tech threads etc.. Smaller runners typically improve air charge velocity, this will improve throttle response. Often at the same time the runners get longer, which typically builds torque.. That is why you often see "stacks" you can put between your carb and intake, these are to build torque on Carb cars. Fords EFI by nature builds torque due to its long runner length. The Rover plenum assembly (all things being relative) is more of a HP design, like the aftermarket Ford intakes made by Cartech and Trick flow. On Mustang we typically see people use these "box" intakes in conjunction with turbochargers and blowers as they are VERY free flowing and let the Forced Induction build the torque.. HRMMMM give a guy ideas!!! |
| Larry Embrey |
| That's correct hp is for magazines etc. Larry, I no longer rent a dyno. I also bought a G-tech and a digital fue lair ratio meter and a full function of Datalogger. It has a Bosh wide band O2 sensor and it has about 50 minutes of memory, it then can be download into your PC or lap top. The lap top can also be use to monitor the engine fuel ratio, rpm, throtle posioning etc. up 6 functions and all can be saved in your lap top and compare runs. You can drive with it and check all of the rpm range during actual conditions. The meter combine with the G-tech you actually have a rolling dyno. The one I use is made by Innovate Motorsports LM-1 This combine with a pigy back computer you can chnage fuel maps timing etc. in a FI engine or in a carb change timing and jets. With force induction from a good air intake will not read anything in the dyno due in part that the car is not moving. A good inatake can produce as much as 2 to 3 psi. Just sharing with you. The cost of a dyno tune day can cost as much as $500 for a good day of tuning once. having a meter you can use it anytime. |
| Bill Guzman |
| My Rover 4.6 GT is going on the rolling road on Tuesday. Havent got a clue what power its making. Hoping for 200+RWH Now done 500miles and it really does need a tune up. Will let you know what the figures are. |
| Mark |
| "The Rover plenum assembly (all things being relative) is more of a HP design, like the aftermarket Ford intakes made by Cartech and Trick flow. On Mustang we typically see people use these "box" intakes in conjunction with turbochargers and blowers as they are VERY free flowing and let the Forced Induction build the torque.. HRMMMM give a guy ideas!!!" Larry, the Rover EFI plenum houses individual trumpets for each cylinder for a tuned length. If they need be shortened slightly to allow the package to fit under an un-modified MGB hood, it concedes a little torque. I do think the system would accept forced industion well, but there is not a lot of room for the charger, either super or turbo. |
| Edd Weninger |
| I did not realise that the rover had trumpets inside. That will in fact build torque. |
| Larry Embrey |
| Mark, The camshaft came with an off-set dowel, whic enables you to move the timing slightly forwards or backwards, depending if you want to increase torque or HP. Are you on fuel injection ? My system is a modified Range Rover hot-wire one, with a larger throttle, and shortened, larger trumpets from V8 Developments. I've recently acquired a TVR fueling chip, which I will be substituting for the Range Rover one shortly.....the Race Technology performance meter which I am using is very basic...but adequate to compare mods...didn't want to go to the expense of rolling roads each time I tweeked the car. Mike |
| M Barnfather |
| Mike Im using an Edelbrock carb which worked really well when it was 4.0L. The car feels so much more powerful having a very wide power band. I have now done 700miles, starting to put my foot down and surprisingly it is still keen to rev past 6000rpm. I bought the crank new but unfinished (no keyway)off Ebay and after having a keyway cut the cam timing is retarded by about 4deg. It will be interesting to see what figured the rolling road has. Mark |
| Mark |
| Not a good day The Rolling road was not working and after waiting 4 hours all Ive found out is that its running lean and I need a calibration kit. Mark |
| Mark |
| Mark Which model Edelbrock carb are you using --CFM? And do you know what its calibrated at now --jets , metering rods and springs ? |
| Gil Price |
| Gil Its a 500cfm carb. Metering jets are .083 Metering rods 65/52 Dont know how to tell which springs, they came with the carb. There is a big flat spot at about 2500rpm. I would be very gratefull for some assistance. Thanks Mark |
| Mark |
| Springs should be color-coded. Do you know what the carb. model number is? Wayne |
| Wayne Pearson |
| Wayne The springs seem to have traces of red/orange paint Stamped on the front is 1404 1651 and on the top 8867 There is an Edelbrock badge on the front and on the side the word WEBER cast in. Mark |
| Mark |
| Mark, I would think that you would need with a 4.6 to stay with the stock needles and jets. Using the numbers that would be 1423(.086) main jet and 1460 rod (065x052) in case of doubt have a word with RPI their carb man is called Holly! I asked him if he was changing his name as they have swithed alleigance to Edelbrock/Weber Carbs. Did you get the handbook with the carb,it shows how to lean or richen the mixture but i must admit I didn't find it that simple to understand. Kevin |
| K.R Jackson |
| Kevin Already spoken to Holly, it was him said .083 jets. when I spoke to him Tuesday he said I need a calibration kit which I have ordered. They are also sending me a handbook. Cheers Mark |
| Mark |
| Kevin After looking at the charts on Edelbrocks web site I think you might be right. To correct myself Holly at RPI said he would send the correct jets for a 4.6 which turned out to be .083. There must have been a mistake somewhere. Anyway when the calibration kit arrives Ill fit the .086 jets and see what difference there is. Car is booked in for 3rd Feb for the rolling road. Larry Sorry to hijack your thread thanks Mark |
| Mark |
| Mark, Because we have powerful engines in realitively light cars the engine doesn't have to work that hard so a very light spring is needed. Before I changed to the lightest spring they had I couldn't get my secondaries to open. My Ford 302 had come out of a LTD.As soon as I changed to the lightest spring it was like the jump hyper space, lots of fun now. Worth a try. Chris |
| Christopher Trace |
The secondries on the weber/Edelbrock are mechanical not vacuum, the springs I believe allow the jet to move under load to richen the mixture to avoid a flat spot or bog! as it says in american. Mark where are you having the car dynoed? If there any good you should be able to solve any problems. On my 3.5 the car ran OK on the standard carb jetting before we leaned it off a touch and I think that would be a a good base to start from. Kevin |
| K.R Jackson |
| Thanks Chris Kevin Im going to Sigma engineering in Gillingham Dorset ( not where I went Tuesday ). They have worked on my car before and did a good job. Like all good companies they are very busy. Like you say I will go to the standard jetting by fitting the .086 metering jets, then its just a rod change if necessary. Anyone like to hazard a guess as to what power/torque I should get. Engine spec is 4.6, 10.7:1 comp ratio, RV8 headers, piper 285cam retarded by 4deg, Mallory dual point dist. Ported heads. Thanks everyone for your help Mark |
| Mark |
| Mark. Best guess 240 BHP 296ft/lb Torque. actually this is about the figures for a similar spec engine from V8 Developments they have dyno graphs for several different stages of tune some of their kit would really make your mouth water and your bank manager cry. I am assuming that your heads are standard and the high compression is because of the smaller volume combustion chambers. Mild head mods with the rest of your set up should yield about 270BHP at 5500RPM. Make sure they strap it down well as Larry suggests and have fun! Kevin |
| K.R Jackson |
| Calibration kit came today and guess what? The kit does not have the .086 jets, so Ive had to order them. I just want to drive it! |
| Mark |
This thread was discussed between 11/01/2005 and 28/01/2005
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