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VALVE SPRINGS

Say NO to valve float...

 LINDSEY VALVE SPRINGS


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 STOCK VALVE SPRINGS


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When it comes to upgrades, the valve train is one thing that is seriously overlooked in the 951 engine. The effect of boost on the valve train is very important to consider, the first part of this discussion will focus on the valve spring. First off you must consider the parameters that this engine was designed around. From the factory, this engine's red line was 6400 rpm and was limited to 11.8 pounds of boost by the computer via the cycling valve. Porsche used a valve spring in this engine that was designed to operate within these limits, but they cannot handle a lot more. Read on to further understand just why that is.

When you start increasing the boost pressure, you also increase the force that is trying to prevent the valve from closing. The stock intake valve is 45 mm in diameter and has a 9mm-stem diameter. The factory valve spring has a seat pressure of 130 pounds and an open pressure of 230 pounds. When you calculate the surface area of the valve, it comes out to be just over 2.3 square inches. This means that when the valve has 11.8 pounds of boost pushing against the backside of the valve, it takes approximately 27 pounds of spring pressure to counter the effect of the boost pressure.

When you increase the boost pressure, for example, by increasing the boost from 11.8 pounds to 18 pounds. Now when you multiply the 18 pounds times the surface area of the valve and you now need over 41 pounds of spring pressure to control the valve, that is an increase of 14.2 pounds. Larger intake valves or higher boost pressures will make this problem even worse.

If that is not enough to convince you, consider this: The valve spring actually does two things, not only does it control the valve, but it also has to be able to control the weight of the hydraulic lifter, which happens to be over 100 grams each. Porsche designed their spring rate to handle this very heavy hydraulic lifter at the factory red line of 6400 RPM. With the aftermarket chips today, a red line of over 7000 RPM is commonplace. The inertia of the heavy lifter at that RPM adds significant stress to the valve spring.

All of this discussion so far has revolved around the stock camshaft. The stock cam has an intake lift of .472 and a duration of 223 degrees. Imagine what happens to the spring and lifter when you increase both of these values. The most popular aftermarket camshaft is the Web #274 grind. This cam has a lift of .480" and a duration of 234 degrees on both the intake and exhaust. The more aggressive duration and the ramp speed of the lifter with this duration adds even more stress on the lifter as well as the valve spring. These faster ramp speeds require higher open (nose) pressures to keep the lifter in contact with the cam. If the nose pressure is not high enough, the lifter can actually be thrown off the lobe of the cam (referred to as lofting). Depending on the severity of this, the lifter can now be slammed back against the cam with a hammering effect. This can be serious enough to actually fracture the surface of the cam lobe. Once this begins, it can quickly lead to the lobe being worn down and it can even pound down the face of the lifter and to the extreme, wear holes completely through the face of the lifter. See the photos showing this extreme situation.



Click here.

When you combine the effect the additional boost pressure has against the intake valve with the weight of the lifter operating at 7000 rpm and the added stresses from a more radical cam, it doesn't take long to see that it takes more spring to properly control both of these critical functions.

Lindsey Racing is now offering a high quality spring, which has a seat pressure of 146 pounds at the manufacturer's recommended installed height. This is enough spring pressure to handle 20 plus pounds of boost pressure and can handle valve lift of over .500". If you are going to run higher boost pressures than that, we offer an upgrade to the inner spring that increases the seat pressure even more. Our racing springs are heat-treated, shot peened, polished, and then a final step that most spring manufacturers don't do is they are low temperature stress relieved.

These springs are set up at a different installed height than the factory spring and require the use of our custom spring cups and moly or titanium retainers to properly establish this critical height. This spring package is listed on this web page.

There are some additional components available that will help the problems I have listed here:

  • Lightweight titanium valves are a big help, but these are also very expensive. Typically you only see this type of valve used in a serious racing engine and they have drawbacks in a normal street engine. These are listed in the cylinder head section.
  • Lightweight titanium spring retainers are much less costly and they do help to reduce the weight that the spring has to control. You can find them listed with our valve spring options.

  • There is now another option you have for reducing this valve train weight - solid lifters. For more information on the significant benefits of this modification, look at the technical information included in that part of the web page. "Solid Lifter"

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INTERNATIONAL ORDERING



TO OUR INTERNATIONAL CUSTOMERS:


In the past, we have used a separate order form for placing International orders. We have quit using that process and are requiring all customer to use the shopping cart system built into the web site and it's check out process.

If you simply want a quotation and are not ready to place an order, then cut and paste the contents of your shopping basket, take a screen shot of the basket, or make a list of items and send us a email requesting a quotation with shipping.

If you need shipping prices before you make your final decision to purchase, then you should request that quotation by email and not use the shopping cart checkout process because you will be paying for the parts at that time.

Since our shopping cart and shipping estimator will "NOT" correctly calculate shipping charges on International Orders, we have it set-up to where the shipping will be Zero Dollars ($0.00) when checking out. When the shopping carts address process learns you are not in the United States by selecting your particular country, that's when it switches to equal Zero. That does NOT mean shipping is free.

Upon completion of the check out process, you will have paid for your parts but NOT the shipping on those parts.

Once we look over your parts ordered and calculate shipping weights and box sizes, we will send you an E-Mail with at least one shipping option and maybe several. We utilize UPS, DHL and the United States Postal Service (USPS) to deliver your parts.

Once you pick a shipping carrier and agree to the quotation by returning the E-Mail, we will be sending a PayPal money request for the amount of the shipping to be collected. If the parts are expected to be shipping out quickly, then you may receive that email quickly. If the parts are going to need to be built or something is on back order from the list of parts, we may hold off sending that E-Mail until we have the shipment ready to go. It can vary from order to order as to how we do that. If you think you should be hearing from us quickly, but you don't, feel free to contact us.

If you have special shipping needs or requirements, during the checkout you will see a SPECIAL ORDER INSTRUCTIONS window. Enter that special information there.

A good bit of our business is International and we have been taking care of those valued customers since 1999.

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TURO LEVANEN

'88 944 TURBO S 3 Liter Street Legal Track Racer!

This car is the only one driven both daily on the street and in the Nordic Porsche Sports Cup series.





Engine Mods Include:

3 Liter 968 block bored to 105 mm
LR 65 Turbocharger (LR)
3” to 5” exhaust (LR)
Stainless steel 3” downpipe (LR)
Sport headers (LR)
Catcam cam
Link engine management and all new electrical wiring
Old mechanical rotor ignition changed to coil pack / EMS / digital ignition with new TDC measuring
Flex fuel for 85 ethanol to 98 gas--all mixtures go
Head with 48 mm intake valves
Comet 3 layer head gasket (LR)
140# valve springs (LR)
5 angle seat grind
Larger Intercooler with aluminum hardpipes w/ silicone hoses
LR silicon water hoses
LR fuel rail with 92 lb injectors
Intake Manifold – extrude honed and polished
Racing fuel pump with new hoses
Tial 38mm wastegate
Solenoid over boost controller. Two programs (1.0-1.3 bar). 400 hp-500 hp
Wössler pistons (105 mm 8.5:1 compression) LR
Pauter con rods LR
Light battery in race mount and cut-off switch
Silicon vacuum lines LR
Rod bearings, main and balance shaft bearings Calico metal coated
Oil Pan and Balance Shafts Reseal
Recent radiator, water pump, rollers, belts etc. new – Gates Kevlar/Blue Timing belt
Approx. max horsepower 480 rwhp with 720 Nm torque (531 ft/lb) with substantial dyno hours


Driveline/Transmission:

SPEC Stage 3 Clutch LR
Heavy duty motor mounts
Heavy duty trans. mounts
Recent Clutch Master/Slave with hoses
Heavy duty drive shafts LR
Torque tube with heavy duty bearings
Quaife mechanical differential
All wheel and drive shaft bearings new
All bushings non-OEM


Brakes:

GT3RS 997 brakes and 350 mm slotted and cross drilled rotors
Turbo s rear brakes
Brake bias valve changed


Suspension:

Koni Sport Front
Koni Series 30 racing rear
Front 500 lbs coil springs
Rear 900 lbs coil springs
Adjustable front camber plates
M035 sway bars LR
Elephant Racing Polybronze spring plate bushings
Poly bushings everywhere else
Front solid bushing ball joint kit
Strut tower bar
Lower caster block bar
New front and rear wheel bearings
Recent race alignment and corner balance


Body:

Front/Rear tow hooks
Fire extinguisher system in cabin and engine bay
Fender flares
GT3 front splitter
Rear diffuser in process
968 rear lights and bumper carbon fibre
Sunroof removed (GT parts)
997 gt2 rear wing
Glass fibre hood
Plastic rear window


Interior:

Sparco/GT3 Speed Seats (R & L) in black
Porsche GT3 Steering Wheel and hub
Sparco 6pt cam lock harnesses (R & L)
Geiko racing approved gauge
Stock seat belts remain functional
Track Mats, steel plates and Lightened pedals aluminum
Extra long shifter stick and short shifter
Electrical boost control 2 programs – center console
A/F meter-center console
Fuel pressure meter
Boost meter
Racing “kill” switch in cabin
Full fire ext. system cabin and engine bay with external switch
Back seat delete
Top

INTERNATIONAL ORDERING



TO OUR INTERNATIONAL CUSTOMERS:


In the past, we have used a separate order form for placing International orders. We have quit using that process and are requiring all customer to use the shopping cart system built into the web site and it's check out process.

If you simply want a quotation and are not ready to place an order, then cut and paste the contents of your shopping basket, take a screen shot of the basket, or make a list of items and send us a email requesting a quotation with shipping.

If you need shipping prices before you make your final decision to purchase, then you should request that quotation by email and not use the shopping cart checkout process because you will be paying for the parts at that time.

Since our shopping cart and shipping estimator will "NOT" correctly calculate shipping charges on International Orders, we have it set-up to where the shipping will be Zero Dollars ($0.00) when checking out. When the shopping carts address process learns you are not in the United States by selecting your particular country, that's when it switches to equal Zero. That does NOT mean shipping is free.

Upon completion of the check out process, you will have paid for your parts but NOT the shipping on those parts.

Once we look over your parts ordered and calculate shipping weights and box sizes, we will send you an E-Mail with at least one shipping option and maybe several. We utilize UPS, DHL and the United States Postal Service (USPS) to deliver your parts.

Once you pick a shipping carrier and agree to the quotation by returning the E-Mail, we will be sending a PayPal money request for the amount of the shipping to be collected. If the parts are expected to be shipping out quickly, then you may receive that email quickly. If the parts are going to need to be built or something is on back order from the list of parts, we may hold off sending that E-Mail until we have the shipment ready to go. It can vary from order to order as to how we do that. If you think you should be hearing from us quickly, but you don't, feel free to contact us.

If you have special shipping needs or requirements, during the checkout you will see a SPECIAL ORDER INSTRUCTIONS window. Enter that special information there.

A good bit of our business is International and we have been taking care of those valued customers since 1999.